Manchester United Erik ten Hag has accused Nottingham Forest of "targeting" Bruno Fernandes during their FA Cup tie at the City Ground and branded criticism of the midfielder's behaviour as "pathetic."

United won the game 1-0 thanks to Casemiro's 89th-minute winner but speaking afterwards, Ten Hag said he felt Fernandes had been on the end of a disproportionate number of heavy challenges.

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It was Fernandes' free-kick that gave Casemiro the chance to score and earn United a quarterfinal tie with Liverpool.

"You saw Forest was targeting him," Ten Hag said.

"There were many fouls on him. Maybe I'm a little bit tough but when he has the ball they are really tight on him."

Ten Hag's assessment of the treatment handed out to Fernandes was later put to Nuno Espirito Santo, but the Forest manager disagreed.

"He's a very good player who needs to be controlled but in a fair way, not ever causing any problems or trying to injure him," he said.

"I didn't see what Erik saw."

Fernandes was a doubt ahead of the game against Forest after sustaining a knock on his ankle during the 2-1 defeat to Fulham.

The Portugal midfielder was criticised for going down injured and then jumping up to finish the game on Saturday but Ten Hag condemned any questions surrounding his behaviour.

"I'm not going to say what [injury] he has but it's a serious injury and seeing how serious it was, they criticise him on social media and it's pathetic and can't be," said Ten Hag.

"He has a serious injury but he continues to play on Saturday, he fought to be part of this game. He has a very high pain threshold and last year he did something similar at Spurs and it shows his leadership and that is very good when you are a leader it is flows into the team."