"Cardinals righthander Adam Wainwright pitched through stiffness and discomfort in his right elbow Friday to claim his 20th victory, but he won't try for No. 21 out of concern another start could turn minor irritation into a major setback.

Wainwright will not pitch again this season after being diagnosed Monday with a muscle strain near his right elbow and an inflamed nerve within the joint. A scan of the elbow revealed no additional damage, and team physician Dr. George Paletta recommended late Monday night that Wainwright skip his next scheduled start to avoid stressing the joint and possibly causing a more significant injury.

"All of those muscles are designed to help keep your muscle stable, so when you lose a muscle then it puts more pressure on the ligament and tendons," Wainwright said. "For me to go out there and pitch minus a muscle is not smart. I have a million reasons why I should or could go out there and pitch, but none of them are worth the risk. ...

"The more you do it, the more risk you have."

The club's official announcement, made Tuesday afternoon, labeled the decision "precautionary." Wainwright and two club officials said if the team was in a playoff push he'd pitch.

Wainwright, at 20-11, completes the season as a Cy Young Award contender for the second consecutive year. He and Philadelphia Phillies ace Roy Halladay are the only pitchers in the NL to rank in the top five in the most familiar or significant statistical categories. Wainwright's 20 wins are second Halladay's 21. Wainwright has the second-lowest ERA in the NL at 2.42, behind only Florida's Josh Johnson. Wainwright also ranks third in strikeouts (210) and second in innings (230 1/3) , and he's tied for the most quality starts in the NL this season (25).

A top five finish in this year's Cy Young voting is a trigger for the $21 million, two-year option Wainwright has for 2012 and 2013. To vest the option he must not be on the disabled list at the end of 2011.

The Cardinals righthander injured his elbow while sleeping the night before he won his 19th game of the season. Wainwright said he fell asleep resting his head on his arm, and when he awoke the arm was numb. He wrenched the elbow trying to jerk the arm to his side.

Wainwright called it "a sleeping injury."

He acknowledged that the story behind the injury may be difficult to believe, especially with how information was presented Monday. Wainwright told a reporter he wouldn't need an MRI scan a few hours after he had already had one. Wainwright explained that he felt caught between the club's instructions not to talk about the injury and the fact the injury had been disclosed to the media. He is not the first Cardinals pitcher to get caught in that verbal vice as the team follows a policy that limits what it can say about injuries. Players are often left to explain when the team cannot officially.

The decision to skip his next start was not made until a meeting with the team doctor during the sixth inning of Monday's game. General manager John Mozeliak said that was the first time he was fully debriefed on the extent of the injury."