Messi, who has missed a pair of 1-1 draws for Miami while sidelined with a leg injury, practiced on Tuesday.
"We will see in the training if we are running any type of risk and will evaluate if it's convenient for him to travel or not," Inter Miami coach Gerardo "Tata" Martino said.
Martino would not provide a timetable for the superstar's return, sticking with day-to-day status.
Bowing to Messi's unknown status, the Chicago Fire offered account credits to spectators who show up for Wednesday's clash at Soldier Field.
While a loss wouldn't eliminate Inter Miami from playoff contention, it would be a blow to the squad's hopes of a late charge into the post-season.
With nine wins and six draws from 30 matches, Miami's total of 33 points is five behind New York City FC and four adrift of Montreal for the last available Eastern Conference playoff spots.
Inter, however, has two games in hand on NYCFC and one on Montreal.
Miami's remaining matches include a home contest with overall regular-season champion Cincinnati on Saturday and a home-away set with Charlotte, a rival playoff chaser.
Several Western Conference clubs could join St. Louis in clinching playoff berths, including Real Salt Lake, Seattle, Los Angeles FC, Houston and Vancouver.
