Lester announced his retirement from professional baseball Wednesday, Jesse Rogers of ESPN.com reports.

Lester didn't factor into the decision in Saturday's 8-5 win over the Cubs, allowing four runs (three earned) on eight hits and three walks over five innings. He struck out six.

Lester (7-6) allowed two runs on three hits while striking out two over six innings in a win over the Brewers on Monday.

Lester will start Monday's series opener against the Brewers in Milwaukee, Jeff Jones of the Belleville News-Democrat reports.

Lester (6-6) allowed two earned runs on six hits and no walks with seven strikeouts over six innings, picking up the win in Wednesday's 11-4 victory over the Mets.

Lester allowed one run on six hits and two walks over 5.1 innings in Sunday's loss to Milwaukee. He struck out two and did not factor in the decision.

Lester (5-6) allowed one run on a hit and two walks over 6.1 innings Monday, striking out five and earning a win over the Reds.

Lester allowed one run on seven hits and two walks while striking out four in five innings of Wednesday's 3-2 win over the Tigers. He did not factor into the decision.

Lester (4-6) allowed one run on seven hits and two walks with two strikeouts through 5.2 innings, picking up his first win as a Cardinal in Saturday's 9-4 victory over the Royals.

Lester yielded five runs on six hits and two walks over 5.1 innings in Sunday's loss to the Royals. He struck out two and did not factor in the decision.