Dallas Cowboys' Tyron Smith facing surgery for torn hamstring, possible December return, sources say play Saturday: Tyron Smith's injury will limit Dallas' big-play ability (1:30) Jeff Saturday explains why Tyron Smith's absence will make it tougher for the Cowboys to to run explosive plays. (1:30) 10:15 AM ET Todd Archer Close Todd Archer ESPN Staff Writer Covered NFL since 1997, Cowboys since 2003 Previously covered Bengals and Dolphins Lives in Dallas area with his wife and two children Adam Schefter Close Adam Schefter ESPN Senior Writer ESPN NFL Insider Joined ESPN in 2009 Former president of the Pro Football Writers of America and the author of four books FRISCO, Texas -- Dallas Cowboys left tackle Tyron Smith is unlikely to return before December after his left hamstring tore and came off the bone during Wednesday's practice, sources told ESPN on Thursday. Smith could have surgery as soon as Thursday, pending a potential second opinion, sources told ESPN. He was hurt on a running play and went to the ground as he went to make a block on linebacker Leighton Vander Esch . He was able to walk to the locker room without any help, and the initial tests indicated the ACL in his left knee was intact. Texas-Sized Hole In O-Line Tyron Smith has missed 20 games in the last two seasons for the Cowboys, and the impact he has on the offensive line has been massive: On Field Off Field Yards/Rush 4.8 4.1 Yard/Pass Attempt 7.8 7.1 Sack Pct. 4.2 6.2 -- ESPN Stats & Information Smith was spotted leaving the locker room after practice and did not appear to be limping. The loss of Smith, an eight-time Pro Bowler and protector of Dak Prescott 's blind side, creates a gaping hole on an offensive line that was already dealing with questions before the Sept. 11 opener against the Tampa Bay Buccaneers . Dallas drafted Tyler Smith in the first round to be the left tackle of the future and has used him exclusively at left guard during training camp and the first two preseason games. Smith is also dealing with an ankle injury that kept him out of the past two practices. The Cowboys have played Josh Ball , who was selected in the fourth round last year but did not play as a rookie because of an ankle injury, at left tackle with the first team when Smith has taken breaks. They also drafted Matt Waletzko in the fifth round this year, but he only returned to practice this week after dealing with a shoulder injury for most of training camp. Coach Mike McCarthy has singled out Aviante Collins ' play during camp, but Collins has not played in a game since 2019. He spent most of last season on the Cowboys' practice squad. The Cowboys could look for veteran help either in free agency or the trade market to replace Smith. Eric Fisher , the former No. 1 overall pick in 2013, is unsigned after starting 15 games last season for the Indianapolis Colts . Editor's Picks Dallas' Jones: Gallup won't start season on PUP 10h Todd Archer 2 Related The Cowboys have more than $20 million in salary-cap space, according to NFL Players Association figures, but a good portion of that is scheduled to be directed to the practice squad and in-season call-ups. Tyler Smith took snaps during organized team activities and minicamp at left tackle. He started 12 games at left tackle last season at Tulsa and nine in his redshirt freshman season in 2020. The Cowboys like his strength and makeup but wanted him to focus on one position during training camp. The injury continues a string of injuries in recent years for Tyron Smith, who has not played a full season since 2015 as he has dealt with knee, ankle, neck and elbow injuries. He missed 14 games in 2020 because of neck surgery. He missed six games last season due to an ankle injury and a stint on the COVID list. Smith, who is the longest-tenured Cowboy, turns 32 in December. He is signed through 2023.