Estevao left the pitch after just 16 minutes, and according to coach Liam Rosenior, the player was in tears in the dressing room.
The match against United was Estevao’s fourth since his return from another muscle injury. Between February and March, he suffered a knock that kept him out of Brazil’s squad for friendlies against France and Croatia.
The Athletic reported that the player has sustained a grade four injury, which could jeopardise his World Cup hopes. The club have yet to release the results of the scan, which was reportedly carried out last Monday.
Until then, Chelsea, who are in the FA Cup semi-finals, will have to do without him.
In the Premier League, the London side are seventh with 48 points, just two points off the top six. Estevao has scored eight goals and provided three assists in 36 appearances for the Blues.
If the injury is confirmed, Estevao will have little time to get fit for his first World Cup. He is one of the main players in the Brazil squad managed by Ancelotti.
For Brazil, he has 11 caps and five goals, four of which have come in his last four matches.
Ancelotti will announce his final squad on May 18th, with Brazil’s opening match scheduled for June 13th, against Morocco. Scotland and Haiti are also in the group.