Washington Nationals ace Stephen Strasburg left Friday night's game against the Atlanta Braves with muscle issue in his bac, according to the Washington Post.
Strasburg appeared uncomfortable as he pitched in the second inning, despite twice hitting 98 mph with his fastball.
After giving up a home run to the Braves Freddie Freeman and striking out Evin Gattis, Strasburg threw two consecutive changeups, the pitch he threw in 2010 when his ulnar collateral ligament snapped.
The next six pitches were all fastballs in the 93-95 mph range.
Strasburg, 24, was examined after the inning while in the dugout by pitching coach Steve McCatty and trainer Lee Kuntz, and he did not come out to pitch in the third.
Strasburg was making his 12th start of the season. He entered Friday night's game with a 3-5 record and a 2.49 ERA with 71 strikeouts in 72 1-3 innings.
Strasburg underwent Tommy John elbow ligament replacement surgery during his rookie year in 2010. Last season, general manager Mike Rizzo shut down Strasburg in September as the Nationals headed into the playoffs.
Strasburg has struggled this season and has had concerns about the health of his pitching arm.