FRISCO, Texas -- The Dallas Cowboys will be without three-time Pro Bowl left guard Tyler Smith for the next four to six weeks. Head coach Brian Schottenheimer announced on Monday that Smith will undergo surgery on his left thumb on Tuesday, which will result in his placement on injured reserve, designated to return. That comes with a four- to six-week return period. Dr. Steven Shin will perform Smith's surgery.

"At the end of the day, I felt like he couldn't do the things that he had to do at a high level," Schottenheimer said Monday. "This is a long season, and it's unfortunate. But that's why we coveted T.J. Bass. ... I think he's played a lot of really good football for us, and we expect he'll continue to do so." 

Schottenheimer said the left thumb had been bothering Smith all of training camp, but he couldn't pinpoint a specific moment where the injury occurred. 

"It's just one of those deals that at the end of the day, we made the decision that we all did, that the best thing is to get in front of this thing. It's a long season, let's go get it fixed," Schottenheimer said. "I think at the end of the day, you always see if you can play through these things. He's done things like that, like a lot of guys out there do. Unfortunately, when you're an offensive lineman, grip strength and things like that are really important. We know he's a quick healer, and we want to get it fixed. He'll be back before too long."

Smith will be replaced by fourth-year, undrafted veteran T.J. Bass, 27 years old, as the starting left guard. Bass has played in 48 games since 2023 with 10 starts, 5 of which came in 2025. Dallas valued him so highly that they placed a second-round tender on him in restricted free agency. He's allowed just two sacks and 15 quarterback pressures on 568 career pass-blocking snaps.

"Ton of confidence. Tyler Smith is a great player, but we feel really confident in T.J.," Schottenheimer said. "He's put great film on here. He's played next to [center] Cooper Beebe, played next to [left tackle Tyler] Guyton. That's nothing new, the communication and all that stuff. We tendered him because we trust this guy as a football player, and he's a damn good football player."

Depending on how quickly Smith heals from his left thumb surgical procedure on Tuesday, he could return for "Thursday Night Football" against the Tampa Bay Buccaneers in Week 5 or at the Green Bay Packers on "Sunday Night Football" in Week 6.