Adam Wainwright was a cheerleader on the St. Louis Cardinals' 2011 World Series title team, out the entire year following reconstructive elbow surgery, suiting up and slapping fives in the dugout.

The staff ace of the NL Central leaders might be reduced to that status again from an injury that came with him batting.

The two-time 20-game winner was set to undergo an MRI exam Monday to determine the extent of an injury to his left Achilles and ankle. He's already on the 15-day disabled list and the team was bracing for bad news, leaving the 6-foot-7 right-hander to put a brave face on a dire scenario.

"There's nothing I can do about it, so might as well not be nervous about it or worried about it," Wainwright said after Sunday's 6-3 loss at Milwaukee. "Worry doesn't do anybody any good."

The 33-year-old Wainwright had to be helped off the field after getting injured stumbling out of the batter's box after popping out in the fifth inning Saturday, saying the "foot just shut down on me."

"Unfortunately, it is not great news," general manager John Mozeliak said in a video on the Cardinals' website. "Any way you slice it, he is going to be missed for a while and potentially losing the season is very real."

Several published reports said the Cardinals expect Wainwright to be out for the season. Manager Mike Matheny would only say the pitcher will be examined when the team returns to St. Louis.

"I don't like to speculate until you have the full information, but if you ask me how I feel ... not good," Mozeliak told the St. Louis Post-Dispatch. "All those rumors floating around seem to have some validity to them."

Lefty Marco Gonzales, coming off a strong finish to his rookie season, is the likely long-term rotation replacement. But the 23-year-old Gonzales is also on the DL at Triple-A Memphis with tightness in his shoulder after making three minor league starts.

"I don't think he's going to be ready right out of the box, but not-too-far future I think he's going to be an option," Matheny said.

Other possibilities for Thursday's start at home against Philadelphia are middle reliever Carlos Villanueva and minor leaguers Tyler Lyons, Tim Cooney and Zach Petrick. Lyons pitched with St. Louis last year.

"I'll just cover the whole thing and say we're looking at everybody and try to think long-term, try to think short-term and have a long list of guys that we think could come in here and help us out," Matheny said.

Several top pitchers have missed much or all of a season in recent years, among them Matt Harvey, Yu Darvish, Jose Fernandez and Zack Wheeler. None of that group were sidelined because of hitting.

Wainwright, who is 2-1 with a 1.44 ERA in four starts, was hurt a few days after Washington ace Max Scherzer injured his thumb batting. Those kind of incidents are likely to ramp up the long AL vs. NL debate on the designated hitter, as in whether it's worth having pitchers bat.

The three-time All-Star is 121-67 for St. Louis, and was their star closer in place of injured Jason Isringhausen in 2006 when they won the World Series.

Helped by Wainwright, the Cardinals have reached the National League Championship Series in each of the last four seasons. They lost to Boston in the 2013 World Series.

"You have to move beyond it," Brewers manager Ron Roenicke said before Sunday's game. "A couple years ago, we lost our 3, 4, 5 hitters for the year. The season-ending ones are tough."

Before Sunday's loss, Matheny said any length of time without Wainwright would be tough.

"I think the test is going to be, with Adam, and everyone in here can see, the difference in our attitude," Matheny said. "We treasure every win we have, but it was different in here last night. We're just going to hopefully let the guys go back out there and play."

"They had a little time to think about some of this and the response and the answer is, we knew that some tests were going to come. And, this is a big one that we're getting early. Let's see what we're made of."

Like Michael Wacha before him, Gonzales made it to the majors less than a year after being drafted in the first round. He was in the running for the fifth starter spot in spring training along with Carlos Martinez and Jaime Garcia but began the year as the opening day starter in Memphis.

Garcia had the inside track on the fifth spot before experiencing a setback in his comeback from thoracic outlet surgery and he's also on the DL, working his way back.

Lance Lynn, the losing pitcher Sunday, said there was no extra pressure to step up and fill Wainwright's shoes.

"No," Lynn said, "we've just got to be ourselves."

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AP stringer Jim Hoehn contributed to this report.