Washington Nationals starting pitcher Stephen Strasburg is going back on the injured list.

Manager Dave Martinez said Monday that Strasburg experienced discomfort Sunday after he threw a bullpen session on Saturday and was set to have an MRI. He had been scheduled to start Tuesday night against the Atlanta Braves after making his season debut last week.

"He threw his bullpen [on Saturday]. The next day he didn't feel so good,'' Martinez said. "We were hoping it was just something that would go away. It didn't. Today, we sent him to get an MRI. We don't have any results back yet.''

The 33-year-old right-hander allowed seven runs, eight hits and two walks in 4⅔ innings against the Miami Marlins in that start, taking the loss. He also struck out five and hit a batter while averaging just 91.9 mph with his fastball.

"He said he felt good after the game,'' Martinez said. "He said [his] legs felt fatigued, which was normal. But other than that, he said he felt fine.''

Before that, the three-time All-Star and 2019 World Series MVP had not pitched in a major league game since June 1 last year, spending much of the time recovering from surgery on July 28 to correct thoracic outlet syndrome, a compression of nerves, arteries or veins near the neck or armpit. He had made three minor league rehabilitation starts.

The Nationals signed him to a seven-year, $245 million extension in December 2019, but because of injuries, he has made just eight major league starts since signing that contract, going 1-4 with a 6.89 ERA in those games.

The former No. 1 overall pick is 113-62 with a 3.24 ERA in his major league career.

The Associated Press contributed to this report.