Manchester United legend Roy Keane has admitted he is concerned how Erik ten Hag's side will respond if they go behind to rivals Manchester City in the FA Cup final.
United are looking to deny City the chance to win the treble, with Sir Alex Ferguson's 1999 side the only club to have won the Premier League, Champions League and FA Cup in the same season.
City have already retained the league title and are set for blockbuster showdowns with United in the FA Cup final and Inter Milan in the Champions League final. Ten Hag has already vowed they will "give everything" to wreck City's treble hopes, stating: "We will have to play the perfect game.
"It was the perfect game we played this season when we beat them and we have to go again, we know that. We will give everything and when I say everything, that is everything - the fans can rely on that.
"We will do everything to give them the second trophy - everything I have, everything the team have and everything the staff have, to get it done. We can do it, because we have proved it already. It's not easy though, because they're a great team, but we also have a great team."
However, former captain Keane, who lifted the FA Cup on four occasions during his time at Old Trafford, is worried United's weaknesses will be exposed if Pep Guardiola's side take an early lead. "My worry for this United team is when they've gone behind and have been up against it, they've gone under very easily," he said on The FA Cup Special Overlap.
"There's lots of occasions – Liverpool, Sevilla, Brentford, City – you'd hate for that to happen at Wembley against City. If City score early, you might start seeing United's weaknesses right in front of you. That first goal is huge.
"People were writing Manchester United off against Brighton, as if United couldn't cope against Brighton, who were doing well at the time, but they turned up – and they get over the line in the big games.
"They are a bit better [than they were], but on paper, Manchester City are favourites – but that just might suit United. It could be a fight for the first hour [against Manchester City] and just hanging in there, even with the players Manchester United have."
However, Keane also believes the fact that "United have been written off" is "dangerous", adding: "United have players like Bruno Fernandes and Marcus Rashford who can hurt City. Wembley, the atmosphere and the fact that United have been written off – it's dangerous."
Roy Keane was speaking on The FA Cup Special Overlap, in partnership with Sky Bet
