Manchester United clawed back from a goal down to beat Leicester City in a 2-1 fourth-round FA Cup victory on Friday at Old Trafford, thanks to a last-gasp controversial header from veteran defender Harry Maguire plus a strike from Joshua Zirkzee.

The game appeared to be heading into extra time before Maguire headed in the winner in the 93rd minute from Bruno Fernandes' free kick, seconds before the final whistle.

"The second half we played a little bit better, with a little more speed, winning second balls," United manager Ruben Amorim said. "Then we managed to turn things around so it was a good result, not a good performance."

Television replays showed Maguire appeared to be offside, but the linesman did not raise his flag and VAR is not used in the FA Cup until the fifth round.

Asked about losing in "Fergie time" -- famously coined in reference to manager Alex Ferguson's United teams frequently scoring in stoppage time -- frustrated Leicester boss Ruud van Nistelrooy said: "We are not defeated in Fergie time, we are defeated in offside time.

"(VAR) wasn't necessary," he added. "Look, VAR you have a couple of centimetres, couple of inches. This was half a metre clear in line. It's a hard one to take. We deserved to go into extra time and go for the battle in extra time and maybe penalties."

The result handed United only their third win in their last eight games at Old Trafford across all competitions, and the fans something to cheer about after a smattering of boos saw the team off at halftime.

"A great finish to the game," Maguire told ITV. "The second half we played a lot better. The first half was nowhere near good enough, we played at a slow tempo and we didn't really get going. We probably deserved to go into halftime losing."

Holders United were indeed poor in the first half and Leicester capitalised in the 42nd minute when Wilfred Ndidi's shot was blocked by keeper Andre Onana but Bobby De Cordova-Reid was there to head in the rebound from close range.

Zirkzee levelled in the 68th minute when Alejandro Garnacho sent a cross into the box but Rasmus Hojlund's effort was blocked by defender Caleb Okoli. The ball fell perfectly for Zirkzee to tap home just three minutes after he entered the game.

Garnacho made an immediate impact down the left as a second-half substitute and squandered a terrific chance when he tried to squeeze a shot inside the near post but hit the side netting, with a frustrated Rasmus Hojlund open in front of goal.

Amorim pointed the blame squarely at himself for United's struggles.

"The coach is the first responsible, when one team doesn't perform, doesn't improve, it is the coach," he said. "But we are here to do things and to see the game, to study the game and try to improve for the next game."

(Reuters)

Maguire heads Manchester United into FA Cup fifth round