Romelu Lukaku celebrates with Alexis Sanchez and Jesse Lingard after scoring against Huddersfield on Saturday. Photo: Reuters

Debate over the merits of video assistant refereeing was again raised as a Romelu Lukaku double eased Manchester United into the FA Cup quarter-finals in a 2-0 win at Huddersfield despite a controversial call going against Jose Mourinho’s men.

Juan Mata thought he had put United into a 2-0 lead just before halftime, only for the Spaniard’s effort to be ruled out by the video referee after a lengthy delay, and without conclusive proof the officials on the field had made the wrong decision.

Thankfully for United, and the authorities, that decision didn’t have a definitive influence on the outcome as Lukaku struck early in both halves to take his tally for the season to 21.

Brighton and Southampton were also fifth-round victors to join Chelsea and Leicester, who beat Hull and Sheffield United respectively on Friday, in the draw for the last eight later on Saturday.

United were without Paul Pogba due to illness as a frustrating few weeks for the Frenchman continued after a dramatic dip in form that has seen him hauled off by Mourinho in recent defeats at Tottenham and Newcastle.

Mourinho made six changes in all from last weekend’s shock reverse at St. James’ Park, but his decision to retain Lukaku paid dividends when the Belgian burst on to Mata’s pass to open the scoring inside three minutes.

Mata then had the ball in the net himself a minute before the break. A delay in referring the decision was exacerbated as the lines used to help the video official decipher offside decisions appeared to be far from straight.

United were left to mull over their grievance at halftime, but quickly ensured it wasn’t to cost them too dearly as a brilliant one-two between Lukaku and Alexis Sanchez freed the former to slot low past Jonas Lossl.