Ruben Loftus-Cheek suffered a suspected ankle injury in Chelsea's 3-0 friendly win over New England Revolution on Wednesday.
Maurizio Sarri's men continued their preparations for the Europa League final with a comfortable victory, but they were dealt an injury blow in the untimely charity friendly.
Loftus-Cheek, introduced at half-time, came off after appearing to hurt his ankle at Gillette Stadium.
The midfielder went down under a challenge and was in discomfort before being replaced in the 69th minute, the injury a blow ahead of the May 29 decider against Arsenal in Baku.
The friendly looked to be going well for Chelsea, with Ross Barkley scoring a brace to go with an Olivier Giroud header.
READ: Championship Playoffs: Derby County stuns Leeds to reach final
Barkley scored in the third minute before Giroud headed in Davide Zappacosta's cross just prior to the half-hour mark as Chelsea outclassed the MLS outfit.
Gonzalo Higuain, who struck the crossbar early in the second half, had an effort hit Barkley before going in to make it 3-0.
But Loftus-Cheek's ankle injury soured what was an otherwise comfortable outing for Chelsea.