Harry Maguire scored a controversial injury time winner as Manchester United came from behind to beat Leicester 2-1 and move into the last 16 of the FA Cup on Friday.
United went behind to a Bobby De Cordova-Reid goal four minutes before halftime. Joshua Zirkzee equalized in the 68th minute and Maguire grabbed the late winner.
There was a heated debate over whether the England center half was in an offside position but there is no VAR in the FA Cup and the goal stood.
"This (loss) wasn't necessary," an unhappy Leicester coach Ruud van Nistelrooy told broadcaster ITV.
"This was half a meter (offside). Then extra time, stay in the game, you never know what happens. We deserved to go into extra time and maybe penalties. Decisions like these in our level are hard to swallow.”
The result marked the first time in United's history that the club has won three times at home against the same team in the same season. United beat Leicester 5-2 in the League Cup and 3-0 in the Premier League at Old Trafford.
The result was a boost for new coach Ruben Amorim and a bitter letdown for Van Nistelrooy, who was the interim manager at United before being moved on and taking charge at Leicester.
Leicester, a one-time FA Cup champion, was 1-0 up at the break. Manuel Ugarte was dispossessed near the touchline and Bilai El Khannouss' low cross was hit goal-bound by Wilfred Ndidi but deflected in off De Cordova-Reid.
The introduction of substitutes Alejandro Garnacho and Zirkzee lifted United in the second half and Zirkzee got the equalizer with the simplest of finishes after good work from the Argentine player down the left flank.
Then, just as the game looked like going into extra time, Bruno Fernandes threw a long ball into the box for Maguire to head the winner.
“(It was a) great finish to the game,” Maguire said. “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.
“He (Garnacho) made a big impact. He always does that when he comes off the bench, so credit to him, he's ready, he's focused.
