Adam Wainwright won his 19th and 20th games while nursing a right forearm strain hurt in a freak accident at home. Now, the team doctor recommends he shut it down for the year.

The 20-game winner underwent an MRI exam on Monday that revealed a strained muscle in his forearm and inflammation near the elbow, and team physician Dr. George Paletta recommended that Wainwright not pitch again this season.

Manager Tony La Russa said he'd go with Wainwright if the Cardinals bucked astronomical odds and made it to the last day still in postseason contention. The Reds' magic number for clinching the NL Central was one entering Tuesday night.

La Russa called the decision precautionary.

"I think it's smart, he's pitched enough, he's had a great year. If we get to Sunday and we've won five in a row and they've lost five in a row, then he'll pitch Sunday. How about that?" the manager said.

The Cardinals believe Wainwright will be fine with rest. The pitcher said the elbow ligament is not an issue.

"My ligament looks exactly the same as it did before, everything is perfectly intact," Wainwright said. "It's really a non-issue to be honest. If we're going to the playoffs, I'm pitching."

Wainwright is 20-11 with a 2.42 ERA, both second-best in the National League. He's also second in innings (230 1/3) and third in strikeouts (213) and most of the season has been among the top contenders for the Cy Young Award.

Jake Westbrook will take Wainwright's scheduled start on Thursday.

Wainwright said he slept on the arm earlier this month, woke up and found the arm numb, and flung it aside instead of waiting for feeling to return.

"I couldn't make this up," Wainwright said. "I know that happens to almost everybody in your life.

"Usually what you do is grab with the other arm and move it to other side and you wait for it to tingle or whatever. It was like 3 in the morning and out of pure laziness what I did was just fling it backwards, and I wrenched my elbow a little bit."

The 29-year-old Wainwright won his 19th and 20th games since the injury while doing rehab between starts.

He then was taken out after six innings and 84 pitches the night he won his 20th game. He said Paletta told him there was a risk of further injury if he kept pitching.

The Cardinals have a two-year, $21 million option on Wainwright's contract for 2012 and 2013 and one of the provisions is he not end this season or next season on the disabled list. Wainwright wasn't worried about that.

"I have a million reasons why I should or could go out there and pitch, but none of them are worth the risk," Wainwright said. "I've got a lot of reasons why if they don't pick up my option I'll be all right.

"Know what I mean?"

The team didn't disclose Wainwright had undergone an MRI until Tuesday. Wainwright said he was told not to talk about it, and thought the team would also wait until test results could be analyzed, but originally said he hadn't had the test.

"I'm an investment and I do what they tell me," Wainwright said. "We still had some decisions to make and whether I was going to pitch or not wasn't 100 percent.

"I was basically given the idea that you could go out and pitch and there's no problem, but you could also complicate it."