CHARLOTTE — For the second time this season, Chandler Zavala is working his way back from IR.
The guard was designated to return to practice on Tuesday, opening his 21-day window to return.
Zavala went on IR with a calf injury on Nov. 29, his second trip to IR this season.
He originally went on IR in Week 5 with a knee injury, but was activated and started three more games before leaving Monday's loss to the 49ers with a calf injury.
He can be activated at any time.
The Panthers also have guard Robert Hunt practicing with the potential to return, and they have an open roster spot.
View photos of action between the Panthers and Rams through the years.
Carolina Panthers' Steve Smith, left, scores on a 68-yard reception after leaving St. Louis Rams' Tye Hill, right, on the turf in the third quarter of their NFL football game Sunday, Sept. 9, 2007, in St. Louis. The Panthers beat the Rams, 27-13.(AP Photo/Tom Gannam)
Members of the St. Louis Rams' Brian Young (66) and Travis Fisher (22) and Carolina Panthers' Muhsin Muhammad (87), Ricky Proehl (center) and Steve Smith (89) dive for the loose football during a fumble following a shuttle-pass during the first half of their NFC playoff game in St. Louis, Saturday, Jan. 10, 2004. The loose ball was recovered by Muhammad for a touchdown. The play was reviewed by the officials and the loose ball and recovery by the Panthers was ruled a touchdown. (AP Photo/James A. Finley)
Carolina Panthers running back Anthony Johnson (23) is seen in action during an NFL game against the St. Louis Rams Oct. 13, 1996, in Charlotte, N.C. (Allen Kee via AP)
Carolina Panthers wide receiver Steve Smith looks skyward after catching the winning touchdown pass on the first play of the second overtime period against the St Louis Rams in and NFC playoff game in St. Louis Saturday, Jan. 10, 2004. The Panthers beat the Rams, 29-23. (AP Photo/Charles Rex Arbogast)
Carolina Panthers running back Anthony Johnson (23) is seen in action during an NFL game against the St. Louis Rams Oct. 13, 1996, in Charlotte, N.C. (Allen Kee via AP)
Carolina Panthers running back Anthony Johnson (23) is seen in action during an NFL game against the St. Louis Rams Oct. 13, 1996, in Charlotte, N.C. (Allen Kee via AP)
Carolina Panthers' Mike Tolbert (35) tries to dive over the goal line for a touchdown against the St. Louis Rams in the second half of an NFL football game in Charlotte, N.C., Sunday, Oct. 20, 2013. (AP Photo/Mike McCarn)
St. Louis Rams quarterback Kurt Warner (13) is sacked by the Carolina Panthers defense during a November 5, 2000 game in the TWA Dome in St. Louis. (AP Photo / Al Messerschmidt)
Carolina Panthers' Cam Newton (1) celebrates a touchdown against the St. Louis Rams during the first half of an NFL football game in Charlotte, N.C., Sunday, Oct. 20, 2013. The Panthers won 30-15. (AP Photo/Bob Leverone)
Umpire Paul King, center, tries to separate Carolina Panthers' Jordan Gross, left, and St. Louis Rams' Robert Quinn, right, in the second half of an NFL football game in Charlotte, N.C., Sunday, Oct. 20, 2013. (AP Photo/Bob Leverone)
St. Louis Rams quarterback Kurt Warner (13) is seen in action during an NFL game against the Carolina Panthers Dec. 3, 2000, in Charlotte. (Allen Kee via AP)
Carolina Panthers' Mike Mitchell (21) sacks St. Louis Rams' Kellen Clemens (10) for a loss during the second half of an NFL football game in Charlotte, N.C., Sunday, Oct. 20, 2013. The Panthers won 30-15. (AP Photo/Bob Leverone)
Carolina Panthers wide receiver Steve Smith (89) runs the ball as St. Louis Rams strong safety Darian Stewart (20) attempts to tackle during an NFL football game in Charlotte, NC Sunday, Oct. 20, 2013. (AP Photo/Mike McCarn)
Carolina Panthers' Star Lotulelei (98) prepares to tackle St. Louis Rams' Zac Stacy (30) during the second half of an NFL football game in Charlotte, N.C., Sunday, Oct. 20, 2013. The Panthers won 30-15. (AP Photo/Bob Leverone)
Carolina Panthers' Captain Munnerlyn (41) celebrates his interception return for a touchdown against the St. Louis Rams in the first half of an NFL football game in Charlotte, N.C., Sunday, Oct. 20, 2013. (AP Photo/Chuck Burton)
Carolina Panthers' Mario Addison chases down St. Louis Rams' Tavon Austin (11) during the second half of an NFL football game in Charlotte, N.C., Sunday, Oct. 20, 2013. The Panthers won 30-15. (AP Photo/Bob Leverone)
Carolina Panthers quarterback Cam Newton (1) scrambles to get away from St. Louis Rams outside linebacker Alec Ogletree (52) during an NFL football game in Charlotte, NC, Sunday, Oct. 20, 2013. (AP Photo/Mike McCarn)
St. Louis Rams quarterback Kurt Warner (13) gets set to throw a pass during an NFL game against the Carolina Panthers Dec. 3, 2000, in Charlotte N.C. (Allen Kee via AP)
St. Louis Rams quarterback Tony Banks (12) gets set to throw a pass during an NFL game against the Carolina Panthers Oct.13, 1996, in Charlotte, N.C. (Allen Kee via AP)
Carolina Panthers running back DeAngelo Williams is pulled down for a 1-yard loss by St. Louis Rams' Adam Carriker during the second quarter of an NFL football game Sunday, Sept. 9, 2007, in St. Louis. The Panthers won the game, 27-13. (AP Photo/Jeff Roberson)
Carolina Panthers quarterback Jake Delhomme calls out at the line during the first quarter of an NFL football game against the St. Louis Rams Sunday, Sept. 9, 2007, in St. Louis. The Panthers won the game, 27-13. (AP Photo/Jeff Roberson)
Carolina Panthers running back DeAngelo Williams, left, looks for a hole during the fourth quarter of an NFL football game against the St. Louis Rams Sunday, Sept. 9, 2007, in St. Louis. The Panthers won the game, 27-13. (AP Photo/Jeff Roberson)
St. Louis Rams quarterback Marc Bulger (10) passes as Carolina Panthers defensive lineman Kris Jenkins defends during an NFL football game Sunday, Sept. 9, 2007, in St. Louis. The Panthers won the game, 27-13. (AP Photo/Jeff Roberson)
Carolina Panthers wide receiver Drew Carter (18) catches a 9-yard pass for a touchdown as St. Louis Rams' Lenny Walls defends during the fourth quarter of an NFL football game Sunday, Sept. 9, 2007, in St. Louis. The Panthers won the game, 27-13. (AP Photo/Jeff Roberson)
Carolina Panthers wide receiver Steve Smith (89) eludes St. Louis Rams Chris Draft, right, during an NFL football game Sunday, Sept. 9, 2007, in St. Louis. The Panthers won the game, 27-13. (AP Photo/Tom Gannam)
St. Louis Rams running back Steven Jackson (39) looks for a hole during the second quarter of an NFL football game against the Carolina Panthers Sunday, Sept. 9, 2007, in St. Louis. The Panthers won the game, 27-13. (AP Photo/Jeff Roberson)
Carolina Panthers' Drew Carter celebrates his first quarter touchdown against the St. Louis Rams in their NFL football game Sunday, Sept. 9, 2007, in St. Louis. (AP Photo/Tom Gannam)
Carolina Panthers running back DeShaun Foster (26) is brought down by the St. Louis Rams' Pisa Tinoisamoa (50) and Ron Bartell (24) after running up the middle for a 15-yard gain during the third quarter of an NFL football game Sunday, Sept. 9, 2007, in St. Louis. The Panthers won, the game, 27-13. (AP Photo/Jeff Roberson)
Carolina Panthers' Jake Delhomme (17) prepares to throw a pass during the Panthers 15-0 win over the St. Louis Rams in an NFL football game in Charlotte, N.C., Sunday, Nov. 19, 2006. (AP Photo/Chuck Burton)
St. Louis Rams' Stephen Davis (48) is brought down by Carolina Panthers' Chris Gamble (20) during the Panthers' 15-0 win in an NFL football game Sunday, Nov. 19, 2006, in Charlotte, N.C. (AP Photo/Chuck Burton)
FILE Carolina Panthers' Keyshawn Johnson (19) breaks a tackle by St. Louis Rams' Fakhir Brown (34) during an NFL football game in Charlotte, N.C., in this Nov. 19, 2006 file photo. (AP Photo/Chuck Burton)
St. Louis Rams' Marc Bulger (10) is sacked by Carolina Panthers' Damione Lewis (92) and Kindal Moorehead during the Panthers' 15-0 win in an NFL football game in Charlotte, N.C., Sunday, Nov. 19, 2006. The Panthers held the Rams to 111 yards, had a team record-tying seven sacks and St. Louis was blanked for the first time since 1998. The win moved the Panthers into a first-place tie in the NFC South. (AP Photo/Chuck Burton)
Carolina Panthers' Richard Marshall (31) runs to recover a fumble by St. Louis Rams' Torry Holt (81) in the fourth quarter of the Panthers' 15-0 win in an NFL football game in Charlotte, N.C., Sunday, Nov. 19, 2006. (AP Photo/Mike McCarn)
Carolina Panthers' Steve Smith (89) catches a touchdown pass as St. Louis Rams' Oshiomogho Atogwe (21) defends during the second quarter of an NFL football game in Charlotte, N.C., Sunday, Nov. 19, 2006. (AP Photo/Rick Havner)
Carolina Panthers' Steve Smith (89) runs past St. Louis Rams' Corey Chavous (25) during the first quarter of an NFL football game in Charlotte, N.C., Sunday, Nov. 19, 2006. (AP Photo/Chuck Burton)
Carolina Panthers' DeAngelo Williams (34) runs past St. Louis Rams' Victor Adeyanju (94) during the second quarter of an NFL football game in Charlotte, N.C., Sunday, Nov. 19, 2006. (AP Photo/Chuck Burton)
Carolina Panthers' Keyshawn Johnson (19) knocks the helmet off St. Louis Rams' Tye Hill (26) during the fourth quarter of the Panthers' 15-0 win in an NFL football game in Charlotte, N.C., Sunday, Nov. 19, 2006. Johnson was called for a face mask penalty on the play.(AP Photo/Mike McCarn)
Carolina Panthers' Nick Goings (37) runs past St. Louis Rams' Typka jackson (97) during the second quarter of the Panthers' 20-7 win in Charlotte, N.C., Sunday, Dec. 12, 2004. Goings, Carolina's sixth-string running back when the season started, ran for 108 yards and one touchdown.(AP Photo/Chuck Burton)
The crowd engulfs Carolina Panthers receiver Mushin Muhammad (87) after his touchdown in the first quarter of the Panthers' 20-7 win over the St. Louis Rams in Charlotte, N.C., Sunday Dec. 12, 2004. (AP Photo/Rick Havner)
Carolina Panthers head coach John Fox greets wide receiver Steve Smith (89) during an NFC Divisional Playoff Game against the St. Louis Rams. The Panthers defeated the Rams 29-23 in overtime on January 10, 2004 in St. Louis, Missouri. (AP Photo/Kevin Terrell)
Carolina Panthers' Mushin Muhammad (87) runs in for a 14-yard touchdown as St. Louis Rams' Travis Fisher (22) falls during the first quarter in Charlotte, N.C., Sunday Dec. 12, 2004. (AP Photo/Chuck Burton)
Carolina Panthers quarterback Steve Beuerlein sets up to pass during the second quarter against the St. Louis Rams, Sunday, Nov. 22, 1998, at the TWA Dome in St. Louis. Beuerlein was 21 for 26 for 211 yards and two touchdowns in Carolina's 24-20 win. Covering is Rams' Roman Phifer (58). (AP Photo/Leon Algee)
St. Louis Rams quarterback Chris Chandler (12) is sacked by Carolina Panthers' Julius Peppers (90) during the first quarter in Charlotte, N.C., Sunday Dec. 12, 2004. (AP Photo/Chuck Burton)
Carolina Panthers quarterback Jake Delhomme (17) throws a pass on the run during an NFC Divisional Playoff Game against the St. Louis Rams. The Panthers defeated the Rams 29-23 in overtime on January 10, 2004 in St. Louis, Missouri. (AP Photo/Kevin Terrell)
Carolina Panthers' Nick Goings (37) dives over St. Louis Rams' Adam Archuleta (31) for a one-yard touchdown during the first quarter in Charlotte, N.C., Sunday Dec. 12, 2004. (AP Photo/Chuck Burton)
FOR USE AS DESIRED WITH 2004 SUPER BOWL STORIES Carolina Panthers defensive end Michael Rucker, left, rushes against the blocking of St. Louis Rams' Orlando Pace during the NFC divisional playoff game Saturday, Jan. 10, 2004, in St. Louis.The New England Patriots take on the Carolina Panthers in Super Bowl XXXVIII on Sunday, Feb. 1, 2004 in Houston. (AP Photo/Charles Rex Arbogast)
Carolina Panthers wide receiver Steve Smith heads to the end zone to score the game-winning touchdown in double overtime against the St. Louis Rams during the NFC divisional playoff game Saturday, Jan. 10, 2004, in St. Louis. (AP Photo/Charles Rex Arbogast)
Carolina Panthers running back Nick Goings (37) heads upfield during an NFC Divisional Playoff Game against the St. Louis Rams. The Panthers defeated the Rams 29-23 in overtime on January 10, 2004 in St. Louis, Missouri. (AP Photo/Kevin Terrell)
FOR USE AS DESIRED WITH 2004 SUPER BOWL STORIES Carolina Panthers defensive ends Julius Peppers, left, and Micheal Rucker watch a field goal attempt during the first overtime period against the St. Louis Rams in the NFC divisional playoff game Saturday, Jan. 10, 2004, in St. Louis. The New England Patriots take on the Carolina Panthers in Super Bowl XXXVIII on Sunday, Feb. 1, 2004 in Houston. (AP Photo/Charles Rex Arbogast)
FOR USE AS DESIRED WITH 2004 SUPER BOWL STORIES Carolina Panthers running back Stephen Davis carries the ball against the St. Louis Rams during the NFC divisional playoff game Saturday, Jan. 10, 2004, in St. Louis. The New England Patriots take on the Carolina Panthers in Super Bowl XXXVIII on Sunday, Feb. 1, 2004 in Houston. (AP Photo/Charles Rex Arbogast)
Carolina Panthers quarterback Jake Delhomme looks over the play on his wrist during the NFC divisional playoff game against the St. Louis Rams Saturday, Jan. 10, 2004, in St. Louis. (AP Photo/Charles Rex Arbogast)
Carolina Panthers wide receiver wide receiver Steve Smith (89) catches a pass during an NFC Divisional Playoff Game against the St. Louis Rams. The Panthers defeated the Rams 29-23 in overtime on January 10, 2004 in St. Louis, Missouri. (AP Photo/Kevin Terrell)
Carolina Panthers wide receiver wide receiver Steve Smith (89) watches from the sideline during an NFC Divisional Playoff Game against the St. Louis Rams. The Panthers defeated the Rams 29-23 in overtime on January 10, 2004 in St. Louis, Missouri. (AP Photo/Kevin Terrell)
Carolina Panthers' Steve Smith runs away from St. Louis Rams Tommy Polley (52) and Adam Archuletta (31) to score the winning touchdown in the second overtime period of the NFC playoff game Saturday, Jan. 10, 2004 in St. Louis. Carolina won 29-23 in double overtime. (AP Photo/Tom Gannam)
Carolina Panthers' Jimmy Hitchcock (37) runs an interception back for a touchdown past the Panthers' sideline in the third quarter of the Panthers' 16-3 win over the St. Louis Rams at Ericsson Stadium in Charlotte, N.C., Sunday Dec. 3, 2000. (AP Photo/Rick Havner)
