Lester showed well down the stretch with the Cardinals last season, but he just turned 38 years old and feels ready to move on from the demands of what was an illustrious 16-year big league career. "It's kind of run its course," the lefty said to ESPN. "It's getting harder for me physically ... I'd like to think I'm a halfway decent self-evaluator. I don't want someone else telling me I can't do this anymore. I want to be able to hand my jersey over and say, 'Thank you, it's been fun.' That's probably the biggest deciding factor." Lester finishes as a five-time All-Star and three-time World Series champion with a lifetime 3.66 ERA, exactly 200 wins, and 2,488 strikeouts. He posted a career 2.51 ERA in the playoffs, the lowest mark of any pitcher to log 150-plus postseason innings.

The 37-year-old southpaw -- perhaps making his final regular season start -- punched out four and walked four in the ballgame. He held the Cubs off the board through the first four innings, but the wheels fell off as he surrendered a grand slam to Trayce Thompson in the fifth. He finishes the season with a 4.71 ERA and 1.51 WHIP over 141 1/3 innings in 28 starts between the Nationals and Cardinals.

Lester has been working through an undisclosed ailment that apparently popped up during his last outing Saturday at Wrigley Field, but it's not something that will require him to miss a turn in the Cardinals' rotation. The veteran left-hander boasts a 2.66 ERA over his last 40 2/3 innings (seven starts) for St. Louis dating back to August 25.

Lester essentially confirmed that he wasn't totally right physically during Saturday's start against the Cubs, but he and the Cardinals haven't divulged any specifics about what he's dealing with. President of baseball operations John Mozeliak said Sunday that the team is "optimistic" about Lester's status, but they are holding off on announcing a starter for Thursday versus the Brewers until they see how the lefty recovers. “It’s just going to be a couple of days to re-evaluate and see,” manager Mike Shildt said. If Lester can't go Thursday, Jack Flaherty would likely make an abbreviated start instead.