According to Jon Heyman of MLB Network, Conforto is expected to undergo an MRI on Monday.
The 28-year-old has showed impressive durability in recent years, playing at least 150 games in 2018-19 and 54 of 60 games in 2020. He ended last season on the injured list with hamstring tightness but has mostly been able to stay on the field as of late.
Any missed time creates a significant hole in the lineup for the Mets considering what he can provide offensively. Conforto entered the day hitting .230 with two home runs in 34 games in 2021.
A one-time All-Star, he has been a reliable hitter for the past few seasons with 88 combined home runs from 2017-19. He was even better in 2020 with a career-high .322 batting average to go with nine home runs and a .927 OPS.
It could be enough to cash in as a free agent in the offseason if he can stay healthy.
New York will struggle to replace Conforto offensively, but the team has a reliable defensive option available in Kevin Pillar.