Washington Nationals right-hander Stephen Strasburg left Tuesday night's start against the Braves in Atlanta because of a tight right trapezius muscle, manager Dave Martinez said after his team's 11-6 win.
Strasburg will have an MRI on Wednesday, Martinez said.
It was his third start since returning from more than a month on the injured list.
Strasburg left after a hard-hit comebacker by William Contreras hit him in the glove and appeared to nick his wrist. Martinez and Nationals athletic trainer Paul Lessard had already visited Strasburg in the bottom of the first inning after he walked Ronald Acuna Jr. on four pitches.
Strasburg was seen shaking his right arm against Acuna and never looked comfortable during his outing, as his fastball averaged just 89.9 mph on the 11 four-seamers he threw. He was averaging 91.9 mph on his fastball entering the game.
The drop in velocity was reminiscent of his second start of the season on April 13, when he allowed eight runs in four innings and averaged 90.6 mph on his fastball. He landed on the IL after that game with right shoulder inflammation.
Strasburg also missed most of 2020, making just two starts after requiring surgery for carpal tunnel neuritis.
"He's frustrated but I want to make sure we do the right thing, for him and for us,'' Martinez said.
Strasburg has been on the injured list 13 times in his career. He is in the second season of a seven-year, $245-million contract he signed after leading the Nationals to the 2019 World Series title, when he won MVP honors with two wins against the Houston Astros and went 5-0 with a 1.98 ERA in the postseason.
The Nationals did beat the Braves 11-6 as Juan Soto finally had a big game, going 3-for-4 with a home run, walk, four runs and four RBIs, but they remain in last place in the National League East with a 22-29 record.
Strasburg is 1-2 with a 4.57 ERA, Patrick Corbin is 3-4 with a 6.23 ERA and Jon Lester is 0-2 with a 4.91 ERA as the Nationals rank 20th in the majors in rotation ERA despite Max Scherzer's 2.34 mark. Scherzer is a free agent after the season, leading to speculation he could be traded if the team doesn't turn it around.