Ed Woodward should not be fooled by the score. While it was comfortable in the end, the clamour for Manchester United to strengthen their attack is going to only intensify after this misshapen performance from their second string. The search must go on, even if Borussia Dortmund hold firm on Jadon Sancho. Ole Gunnar Solskjær made his point when he turned to his bench moments after Dean Henderson had prevented Brighton’s Leandro Trossard from cancelling out Scott McTominay’s goal. After intending to give Paul Pogba and Marcus Rashford the night off, the manager called them into action and United pulled clear to reach the Carabao Cup quarter-finals. “We’re through, so that’s the job in the cup,” Solskjær said. “We deserved it in the end. Some quality moments from some of our players gave us the goals. We defended well. After a difficult start we’ve picked it up. The confidence comes, the sharpness comes. Not a classic performance but scoring goals is always nice.” The pressing problem for United is whether they have enough quality behind their usual attack. They need to add more than Donny van de Beek, whose lovely assist for Juan Mata’s goal showed he is likely to prove a handy signing. An injury to Rashford or Anthony Martial would leave them short up front and Mason Greenwood is too young to play every week but there is no sense Solskjær trusts his reserves to step up when the stars need a rest. Rashford, Greenwood and Martial deserve support from teammates who can keep standards high when they come into the side. United do not have enough weapons for a club of their standing and Solskjær saw that reinforcements are required after bringing in some of the lesser lights for his side’s second trip to Brighton in the space of five days. United were woefully short of creativity during a forgettable opening period, save for one moment of invention that almost resulted in an early breakthrough. After a quiet start Daniel James and Mata combined on the left, carving Brighton open with a swift interchange of passes and freeing Odion Ighalo, who missed an open goal after rounding Jason Steele. It was an isolated flurry from United, who found it hard to get Van de Beek on the ball in the No 10 role. Brighton’s five-man defence was comfortable and the hosts started to play after a timid start. Alireza Jahanbakhsh saw a shot parried by Henderson, David de Gea’s deputy in goal, and Alexis Mac Allister jabbed an effort on to the roof of the net after a winding run from the left. Brighton were holding their own and were kicking themselves after falling behind to a soft goal. Dan Burn was caught out of position and was booked for fouling Mata, who swung the free-kick in for McTominay to head past Steele. “We were in the game, then we were disappointed with the goal,” Graham Potter said. “It was a cheap one.” It was hard not to wonder if Brighton’s manager should have picked a stronger team. This was an opportunity to reach the last eight of a cup and they lacked a cutting edge until Jahanbakhsh went down injured at the start of the second half. On came Neal Maupay, looking to make amends after his last-minute handball gifted United their winning penalty last weekend. United had more to think about with Maupay on the pitch. They tried to play on the break but were unable to keep the ball. James’s dribbles lacked conviction and Ighalo was smothered by Lewis Dunk. At one stage Van de Beek, accustomed to a more cerebral style when he was at Ajax, could be seen urging his new teammates to be calmer on the ball. Brighton almost punished United’s sloppiness, only for Henderson to make a pointblank save from Trossard. Solskjær had seen enough. Rashford and Pogba came on and the game was done when Van de Beek’s beautiful flick released Mata, who finished smartly. “Juan created more or less every moment in this game,” Solskjaer said. “He’s a very valuable member of this squad.” Moments later Pogba’s deflected free-kick flew in from 25 yards. United had finally made their class count.