The 23-year-old went down clutching his left ankle in the first half of Chelsea's 3-0 win over New England Revolution at Gillette Stadium.
Loftus-Cheek has had a breakout season for the Blues and scored for the club in the second leg of their Europa League semi-final tie against Eintracht Frankfurt - a game they would dramatically win on penalties.
The midfielder had to leave the stadium on crutches, fuelling suggestions that he will not be ready to race Arsenal in Baku on May 29.
Following that match, in which the midfielder was substituted to a chorus of boos from the Premier League club's supporters, he backed his manager's decision, telling reporters: "I've played a lot in these last few weeks, more than I've done in my career".
He was absent as the 23 touring players and the chairman, Bruce Buck, visited a Holocaust Memorial on Tuesday but was on the touchline as his team ran out comfortable winners against the Major League Soccer side with two goals from Ross Barkley and another from Olivier Giroud, with Abramovich visiting the dressing room post-match.
The New England Revolution and Chelsea FC relish the opportunity to lock horns for a good cause.
A diving header from Giroud made it 2-0 before the break before Barkley rounded off the scoring just after the hour mark.
The final minutes were marred by concern over Loftus-Cheek's injury, but Chelsea academy prospects Conor Gallagher, Reece James and Trevoh Chalobah were brought on by Sarri as his team coasted to the final whistle.