A day after announcing that rookie right-hander River Ryan will miss the rest of the season with an elbow injury, the Los Angeles Dodgers said Tuesday that he will require Tommy John surgery.

The injury occurred during Rivers' fourth career major league start Saturday against the Pittsburgh Pirates. The 25-year-old underwent an MRI on Sunday morning.

The former two-way player was acquired in a trade from the San Diego Padres in March 2022.

Ryan was 1-0 for Los Angeles this season with a 1.33 ERA and went 4 scoreless innings before departing Saturday's game. He had a 2.22 ERA in eight minor league starts over three levels in 2024, while the Dodgers limited his usage in the minors to 49 appearances (45 starts) over three seasons.

Ryan said he started to feel tightness in his forearm in the third inning Saturday and continued to pitch until he was removed in the fifth after showing discomfort following a pitch to the Pirates' Michael A. Taylor.

"It's part of the game, man," Ryan said after Saturday's game. "The pitch clock definitely makes you speed up a lot. Back in the day, you didn't have to speed up as much when you threw. So throwing back-to-back pitches in 15 seconds, it starts to take a toll."

Information from The Associated Press was used in this report.