"First of all David has been fantastic at the club," manager Ole Gunnar Solskjaer said of under-fire De Gea, who signed a deal until at least 2023 last September.  "He's still fantastic, he's developing and he signed a contract.

"David is working really hard in training, I've been impressed by his work and he's keeping clean sheets, he's still winning games for us with his saves.

"But he's always going to be under criticism because it's Man United. He deals with it, he's mentally very, very strong.

"He's conceded two goals in the last seven games and every goal he concedes it's like 'well, he's finished'. Of course he isn't.

"For me, he's still the best goalkeeper in the world and I wouldn't swap him with anyone.

"We are lucky enough we have Sergio (Romero) as well as a great number two to challenge David.

"And we've got Dean on a long-term contract who we believe, one day, is going to be a challenger to be number one for both Man United and England.

"So we're in a good position there and Dean's development the last few years has just proven that. We want him to keep developing.

"The number one keeper at Man United has the shirt because he deserves to and he's the best one."

Henderson is ineligible to face his parent club when Solskjaer's side welcome the Blades to Old Trafford on Wednesday.

Asked if it made sense for Henderson to stay at Bramall Lane for another season, Solskjaer said: "We need to make sure Dean plays and plays football to develop, so for me we're going to make a decision later on with Dean.

"He's had two fantastic years and we appreciate what Sheffield United have done with him as well so of course that's an option for him to stay at Sheffield United."

Henderson's emergence is a welcome headache at a club that have surely the best pool of goalkeepers in the world, with Sergio Romero, Lee Grant, Joel Pereira, Nathan Bishop and Matej Kovar among the others on the books.

"I think Sergio is the best number two in the world," Solskjaer said. "He's so professional.

"Even though he wants to play every game he challenges David but they're also good friends.

"Every day in training there's a great atmosphere and environment there but of course he's disappointed every time I choose not to play him.

"I've got a good problem, we've got a good problem – a challenge to decide how our goalkeeping department is going to look next season because you can't have three or four top keepers there."

While there is an abundance of goalkeeping options, work is still required in other areas if United are to become title challengers once again.

"Obviously City and Liverpool the last couple of seasons have put the standard where it should be to win the league," he said.

"We've developed over the season and I think now we had a spell of 11 unbeaten, but then you add Paul Pogba and Marcus Rashford to that and you're thinking 'yeah, we're not too far away and I'm very happy with the squad.

"If there are any good deals to be made and players who can make us better, of course we might have to spend some money on that.

"But the squad is great to work with and it's moving in the right direction.

"We're still not where we want to be, close enough to challenge for the Premier League trophy but we take one step at a time.

"Hopefully now we can challenge for the Europa League, FA Cup this season, top four and then let's see how much we can invest for next season."