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The Brazilian was forced off in the first half of Chelsea's defeat to Manchester United last weekend after a sprint down the wing.

Estevao has played 36 games across all competitions in his first campaign with the Blues, scoring eight goals and providing three assists.

He has directly contributed to three goals (two goals, one assist) in as many FA Cup games this term as Chelsea prepare to take on Leeds United in the semi-final on Monday (AEST).

However, the concern for the Blues, and Brazil, is that the 19-year-old also missed games in December and March with muscle injuries, in addition to his current issue.

Brazil's FIFA World Cup campaign begins on 14 June (AEST), when it takes on Morocco in Group C.

"Estevao, unfortunately, won't play for us this season," McFarlane said. "He's going to be out for a little bit of time. That's really unfortunate, especially for someone so young and so talented.

"But we're here to support him and be around him.

"I'm not sure [about the FIFA World Cup], if I'm honest. I just know he won't be available for us. I'm sure he's very hopeful he can make the World Cup, but I don't know on that."

Chelsea has won just one of its past eight games in all competitions, leading to the dismissal of coach Liam Rosenior, although that victory came in the FA Cup.

It thrashed Port Vale 7-0 at Stamford Bridge, while it has also defeated Wrexham, Hull City and Charlton Athletic in the competition this season.

Chelsea has reached the FA Cup semi-finals 28 times, with only Manchester United (32) and Arsenal (30) reaching the final four on more occasions.

McFarlane believes Chelsea will show its true quality at Wembley Stadium after a dismal display against Brighton and Hovel Albion in midweek.

"The performance wasn't good enough. Everyone associated with the club knows that, the players know that," the interim boss added.

"I thought Brighton were very good on the night, and I don't think they got enough credit. They're a really good side with a really good manager. 

"Our performance wasn't good enough, and we're going to address that on Sunday and make sure we perform to the level we know this group is capable of."