Juan Soto exited the game against the Chicago Cubs with back tightness after four innings.
The Mets' star player appeared to wince in pain during his two at-bats.
What happened?
Soto was seen wearing a heating pad in the dugout while in the game.
He made contact on a fly out to left field in the first inning and a lineout to center in the third.
The Mets later announced he exited with left-side back tightness.
Why it matters for Juan Soto
Soto has been one of the best hitters in the majors this season, batting .299 with 17 home runs and a .965 OPS in 61 games.
He missed 15 games in April with a calf strain.
The Mets went 3-12 during that stretch, losing 12 games in a row to fall to 7-16 on the season.
What comes next?
Manager Carlos Mendoza described Soto's status as day-to-day.
Mendoza said he was unsure whether Soto will undergo tests on Wednesday.
Soto was unavailable to reporters postgame.
Mendoza said Soto got treatment during the game, but he got to a point where something was off.
The Mets are preparing to activate Francisco Lindor from the injured list as early as Wednesday.
Lindor has been out since suffering a calf strain in Soto's return from the IL on April 22.
The five-time All-Star played in his third rehab game on Tuesday at Triple-A Syracuse, going 2-for-5 with two runs scored.
Mendoza said team officials will discuss the next step with Lindor and the athletic training staff.
Activation on Wednesday is possible, whether before the first game or between the two games.
The Mets lost the game 9-6.
Soto's injury is a concern for the team.
The Mets are already struggling this season.
Soto's absence could make things worse.
But the team is hopeful he will return soon.
And they are preparing for the possibility of activating Lindor.
The Mets will play a doubleheader against the Cubs on Wednesday.
Soto's status will be closely monitored.
The team will provide updates on his condition.
For now, Soto is day-to-day.
The Mets will have to wait and see how his injury progresses.