Seattle Seahawks quarterback Drew Lock tested positive for COVID-19 on Tuesday, shortly after coach Pete Carroll told reporters that Lock would start the team's next preseason game against the Chicago Bears.

Instead, Lock will miss Thursday's game and Geno Smith will lead Seattle as the team's quarterback competition heads into the home stretch.

Lock not only practiced Tuesday afternoon at Seahawks camp in Renton, Wash., but did so primarily with the first-string offense. Those reps were in part to prep Lock to start against the Bears.

"We had planned well back before the offseason even started to get to this game, the second game," Carroll said after Tuesday's practice. "Geno would be the starter in (the mock game) at Lumen and the opening (preseason) game, then we would go with Drew in the second game. We're trying to follow that if we can."

They won't be able to follow that plan to completion now. The NFL stopped its COVID-19 protocol in March but still follows CDC guidelines that call for five days in isolation after a positive test.

The Seahawks received Lock as part of a massive package in the trade that sent Super Bowl-winning quarterback Russell Wilson to the Denver Broncos this offseason. Seattle did not draft a quarterback and stood pat with Geno Smith, last year's No. 2, and Lock as the main candidates for the starting job.

Lock, Denver's second-round pick in the 2019 draft, has completed 59.3 percent of his passes and thrown for 4,740 yards, 25 touchdowns and 20 interceptions in his career across 24 games (21 starts).

Despite Carroll's original plan to give Lock first-team looks this week, he said he still viewed Smith as the No. 1 quarterback if the season began now.

"Geno's still the No. 1 guy, he's holding onto his spot at this point," said Carroll, who also battled COVID-19 earlier in camp. "I really like what Drew has shown us. You look at his passer rating and some of the stuff he did (in the preseason opener), he did a great job. Both of our guys can play. That's what we do know, they both can play."

Lock completed 11 of 15 passes for 102 yards and a pair of touchdowns in a 32-25 loss to the Pittsburgh Steelers on Saturday.