"We'll see how he does over the next 48 hours," Stefanski told reporters Saturday.
Cooper had three catches for 37 yards in last Sunday's win over Cincinnati but missed a portion of the first half, coming up hobbled with an apparent leg injury in the first quarter after making his first reception. The 10-year veteran logged a full practice on Friday before aggravating his groin today.
For a team looking to improve on a 206-yard offensive effort in the season opener, Cooper's absence likely affects how opponents strategize against a team that prioritizes its rushing attack.
In what was Watson's first season in Cleveland, albeit with 11 games started by Jacoby Brissett, Cooper led the Browns in receiving with 78 receptions for 1,160 yards and nine touchdowns in 2022.
Cooper's availability won't be the only looming question for the Browns on Monday night, however. Starting safety Juan Thornhill (calf) is also listed questionable versus Pittsburgh.
Browns-Steelers is set to kick off at 5:15 p.m. ET on Monday is and is part of a double-header along with Saints-Panthers.