Sonny Gray has a strain in his right hamstring that might jeopardize his Opening Day start for the St. Louis Cardinals.

The right-handed pitcher, who signed a three-year, $75 million contract in November, was pulled off the mound Monday after only 20 pitches against the Washington Nationals.

Initially, St. Louis announced that the three-time All-Star was dealing with tightness, but they updated the diagnosis Tuesday following his MRI results.

“We’ve had some encouraging news that it’s a mild strain. Not going to put any return-to-play [date] on it,” president of baseball operations John Mozeliak said. “It’s been less than 24 hours. We’re going to see how he responds over the next few days. But from the MRI reading, we’re definitely encouraged. Fingers crossed this isn’t something that’s going to linger too long.”

The Cardinals are approaching this with an abundance of caution, as Gray has a history of hamstring strains and missed time twice in 2022 while he was with the Minnesota Twins.

Gray is expected to be St. Louis’ ace coming off a 2023 season in which he finished second in American League Cy Young voting, with an 8-8 record, 2.79 ERA and 183 strikeouts in 184 innings. The Cardinals are trying to bounce back from a 71-91 record and last-place finish in the National League Central.

St. Louis could turn to Miles Mikolas, who started Opening Day last season, to face the Los Angeles Dodgers on March 28. The Cardinals have pitchers Kyle Gibson and Lance Lynn in the fold, too.

A replacement for Gray, however, hasn’t been decided yet. Mozeliak said the team will have more insight in a few days.

“It would be challenging, I think, at this point [for Gray to start Opening Day],” Mozeliak said. “We just have to give it a little air, a little space, and we’ll understand more the next few days.”