RENTON, Wash. -- Seattle Seahawks coach Pete Carroll said quarterback Drew Lock was feeling so sick that he "barely made it off the practice field" on Tuesday, shortly before he tested positive for COVID-19.

"He was dragging," Carroll said Wednesday. "We were going to do post-practice work but [decided] no, let's get him out of here. It hit him. He's had it before already. He's done all of the work to get prepped for it. It just so happens that it got him again."

Lock's latest bout with COVID will sideline him Thursday night for what would have been his first start of the preseason, a setback in his battle with Geno Smith to replace Russell Wilson as Seattle's starter.

Until Tuesday, Smith had gotten almost all of the Seahawks' first-team reps this offseason and had started their mock game as well as last weekend's preseason opener. The Seahawks gave Lock all the No. 1 reps on Tuesday in preparation for his start Thursday night against the Chicago Bears, which Carroll said was their plan all along.

Carroll was asked how much Lock needed the reps that he was going to get against Chicago.

"He did need them," Carroll said. "This week is a screwed up week for a guy to get a bunch of turns and all that. He worked with the ones yesterday in prep for the game, and that's really all he got. I would've liked to see that happen throughout this little mini week. But we'll see what happens next week. We'll figure it out. But it was important and that's where we're going to do extra work after practice with DK [Metcalf] and with Lock, and [Will Dissly], and we just weren't able to do that. So we missed out on that opportunity."

Lock looked so off in Tuesday's practice that Seattle's coaches asked him afterward what was wrong. That's when he reported feeling sick and was told to see the team's trainers.

Smith will start against Chicago before giving way to third-stringer Jacob Eason.

"It came out of nowhere," Carroll said. "Obviously, he will miss this game, but he has a chance to be back; he has a five-day window that he has to take care of it. It's unfortunate. It was his turn to play and start, but we will figure it out. I'm fired up for Geno to go. He had an excellent abbreviated week, had a terrific ... day for us, so he is ready to go. It will also give Jacob a chance to play a little bit more, obviously, and he will get a good shot in the second half. Really, he deserves it and has practiced really well for us, so I'm anxious for him to get out there and play some football."

Lock and rookie running back Kenneth Walker III were the only Seahawks not present at Wednesday's practice. Carroll said Walker is having a "procedure" for what the coach on Tuesday called a hernia. He added that Seattle's second-round pick is expected to be back before Week 1.

Carroll clarified Wednesday that it's not a sports hernia, which typically carries a longer recovery time than a non-sports hernia.

"That's not what he is dealing with," Carroll said. "It's something a little bit different, and we have a chance to get him back quickly."

Carroll said right tackle Jake Curhan (back spasm) will play against Chicago but the status of linebacker Jordyn Brooks (hamstring) for the game is undecided. Carroll expects cornerback Artie Burns (groin) and defensive end L.J. Collier (elbow) to return next week.