NEW YORK -- Yankees pitcher Marcus Stroman had a cortisone shot to treat swelling in his inflamed left knee.

Stroman went to a hospital for scans after the 33-year right-hander mentioned pain to the team following Friday's start, when he allowed five runs and got two outs in a rainy 9-1 loss to the San Francisco Giants.

"The MRI was good, but he had some swelling in there somewhere," manager Aaron Boone said Sunday, "So try to eliminate that, hopefully get him ramped up pretty quick and, hopefully, something that really helps him move it forward."

Stroman was placed on the 15-day injured list Saturday, one day after throwing 46 pitches in steady rain. Boone said he did not know how much time Stroman will miss but hoped his absence would be short-term. Boone said he was uncertain if pitching in rain contributed to the knee issue.

"I'm not even sure," Boone said. "Even watching the video, watching how (he was) not finishing properly on his front leg and I think that was due to the knee."

Stroman is 0-1 with an 11.57 ERA in three starts after allowing a three-run homer to Jung Hoo Lee and a two-run double to LaMonte Wade Jr. in his shortest career start that was not interrupted by rain.

Stroman turns 34 on May 1 and is in the second season of a two-year contract guaranteeing $37 million. The right-hander's deal includes a $16 million conditional player option for 2026 that could be exercised if he pitches in at least 140 innings this year.

Last season, Stroman was 10-9 with a 4.31 ERA in 30 games (29 starts) when he threw 154 2/3 innings, his most since 2021 with the Mets. Stroman struggled in the second half and did not pitch in the postseason, when the Yankees made their first World Series appearance since 2009.