Antony had to be stretchered off midway through the first half against Chelsea after suffering an serious-looking injury.
The Manchester United winger went down following a tackle from Chelsea defender Trevoh Chalobah. No foul was given by the referee, but United put the ball out of play so Antony could receive treatment.
The Brazilian appeared to be in a considerable amount of pain and was substituted for the returning Marcus Rashford. He went down clutching his foot, which appeared to get stuck in the ground as Chalobah made the tackle.
"It’s the reaction of a player that’s going to spend some time out of the game," Gary Neville said on Sky Sports.
"His hand was slamming the ground. I’d be amazed if he does carry on, but he has just stood up.
"He [Erik ten Hag] will now be thinking he’ll have to rethink this game but he’s also got Sunday against Fulham at home to fill in that right-hand side, because Antony would be a shoe-in for that cup final side."
"It's a huge setback," former Manchester City midfielder Michael Brown added on commentary for BBC Radio 5 Live. "He's on a stretcher, the strap comes round the leg which shows you they want to keep control of a certain injury and that's very worrying.
"It's just a late tackle that comes across and he reacted very quickly to say he'd been caught."
United led 1-0 at the time of the injury thanks to an early Casemiro header from Christian Eriksen's free-kick. Erik ten Hag's side know they only need a point from their final two matches of the season to secure a place in next season's Champions League.
Antony has eight goals and three assists in 43 appearances for Manchester United this season. He is now a major doubt for their final Premier League game of the season, against Fulham on Sunday, as well as the FA Cup final, against Manchester City on June 3.
