St. Louis Cardinals ace Adam Wainwright is out at least 15 days because of an injury to his Achilles and left ankle. It could be longer, much longer — possibly even for the whole season.

Hurt while batting Saturday night in Milwaukee, Wainwright was scheduled for an MRI on Monday that likely will reveal how long he'll be gone.

"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."

The 33-year-old Wainwright was put on the 15-day disabled list Sunday. He was hurt while stumbling out of the batter's box after hitting a popup in the fifth inning at Miller Park.

Several top pitchers in recent years have been lost for most of a season or all of it — Matt Harvey, Yu Darvish, Jose Fernandez and Zack Wheeler, among them.

But those were related to pitching, with Tommy John surgery the result. Wainwright had that same procedure and missed the 2011 season when St. Louis won the World Series.

This time, Wainwright got hurt hitting, 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.

Wainwright held a 2-0 lead when he got hurt. He was helped off the field by a trainer and left the game in Milwaukee. The right-hander was wearing a protective walking boot after a 5-3 win over the Brewers.

"My foot just shut down on me," he said.

"It felt like I got hit by something," Wainwright said. "If you look at the replay, I kind of get out of the box and look back to think, 'Gosh, the catcher's mask must have hit me or the bat must have hit me or something must have hit me.' Crazy game, something crazy like that you can never think," he said.

A few minutes after the game, Matheny said the mood in the clubhouse was "pretty somber."

"I don't have any more information than I had for you yesterday," Matheny said before Sunday's game. "Just like I told you before, we're going to wait until tomorrow. He'll fly back with us today. He'll get in the tube tomorrow and we'll a find a little more definitive answer as to what's going on."

Wainwright is 2-1 with a 1.44 ERA in four starts this season.

The three-time All-Star is 121-67 for St. Louis, and was their star closer 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.

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," he said.

The likely replacement in the St. Louis rotation would have been lefty Marco Gonzales, but he's also on the DL at Triple-A Memphis with tightness in his shoulder after making three minor league starts.

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

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.

Other possibilities for Thursday's start at home against Philadelphia are lefties Tyler Lyons and Tim Cooney, and right-hander 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. "Just trying to put it together right now, but not ruling out anybody."

After promising outfielder Oscar Taveras was killed in a car crash last fall, the Cardinals traded Shelby Miller, who totaled 26 wins his first two seasons in the rotation, to Atlanta for outfielder Jason Heyward.

To fill Wainwright's roster spot, the Cardinals also recalled catcher Cody Stanley from Memphis, a sign that star catcher Yadier Molina might need more time to recover from a bruised right knee than first thought. Molina missed his second straight game Sunday.

"He's feeling better, even though we just need to go ahead and take at least another day," Matheny said. 'He can hit, he can run, but squatting is the major issue right now."

It's the first major league call-up for the 26-year-old Stanley, who was batting .216 with two homers in the minors.