Cards play it safe with Heyward's hamstring

ST. LOUIS -- Having already put a third outfielder on the disabled list earlier in the day, the Cardinals watched Jason Heyward last only two innings in Monday night's 2-1 win over the Giants in the series opener.

Heyward was removed from the game due to left hamstring tightness, the severity of which should be better known after another round of tests on Tuesday.

Heyward was making his first start of the year in center field, where he was needed after Randal Grichuk landed on the DL with a right elbow injury. Heyward was seen trying to stretch out his hamstring during his first-inning at-bat, which ended with him striking out. He lasted only one more inning in the field.

"It sounded like ... not necessarily a cramp, but he couldn't get it loose," manager Mike Matheny said. "That was reason for us to have concern, obviously, so we sent him upstairs [into the clubhouse] to get it stretched, and it just didn't get to the point where it felt loosened up to the point that he expected to, so we had to make a move."

This is the third early exit Heyward has made due to injury this season, though none of the issues has been persistent. He left an April game three innings in while experiencing groin tightness. He then departed from a July game when dehydration brought on cramping around his hamstring.

The Cardinals are hopeful this episode is no more serious.

"I thought we were being cautious today," Matheny said. "Jason wanted to go back out there and play defense and see how it loosened up. He said there have been days where one thing or another has been tight, and he has been able to go and figure it out. We made the proactive move of getting him out when we could, and hopefully that pays off."

Video: SF@STL: Grichuk, Adams, Wainwright injury updates

The Cardinals can hardly afford to lose another outfielder to injury, as Matt Holliday, Jon Jay and Grichuk each remain at least two weeks away from a possible return. Heyward has been among the team's most productive hitters, too, during the absence of so many key position players. Heyward, who was not available for comment after the game, homered twice in Sunday's loss and entered Monday with a season slash line of .288/.344/.438.

Tommy Pham replaced Heyward in center after arriving at Busch Stadium around game time. He was recalled from Triple-A Memphis to replace Grichuk on the active roster and Pham went 0-for-3 in the win.