"Had to be cautious," Matheny said. "He could have gone up and hit again, but not at the risk of throwing him out defensively, since we don't know what we're looking at."
The Cardinals expect more clarity to come on Monday, once Grichuk goes through a full evaluation. Grichuk was not available postgame to provide additional details on the injury.
Grichuk, who became the team's everyday center fielder in Jon Jay's absence, has been nagged by various injuries this season. Back tightness cost him time in Spring Training and then resurfaced in April, leading to a month-long stay on the disabled list. Grichuk has more recently been playing through discomfort in his left foot.
"He's a young player trying to figure out how to play through things," Matheny said. "This needs a closer look to make sure that it's something that he can play through. You can't do that midgame without having all that information."
The Cardinals have a back-up center fielder in Peter Bourjos, though Bourjos was not an option to replace Grichuk on Sunday because he had already been used as a pinch-hitter. Matheny said he would also consider Jason Heyward and Stephen Piscotty as center field options if Grichuk is going to miss additional time. At Triple-A Memphis, the Cardinals have Tommy Pham as a ready center field candidate.
Heyward covered center for the final two innings on Sunday. It was his first time at the position since 2013.
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, follow her on Twitter @LangoschMLB, like her Facebook page Jenifer Langosch for Cardinals.com and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.