For much of the afternoon it appeared that Alexis Sanchez’s continued struggles at Manchester United would be the lasting impression.But Romelu Lukaku had other ideas, leading his side to a crucial 3-2 win over Southampton which puts them back in the top four of the Premier League.Sanchez lasted only until the 52nd minute before being suffering a knee injury in the Saints penalty area. Yet his absence was only ever going to be positive after another afternoon to forget in his 14-month United career. Article continues below Editors’ Picks Man Utd ready to spend big on Sancho and Haaland in January Who is Marcus Thuram? Lilian’s son who is top of the Bundesliga with Borussia Monchengladbach Brazil, beware! Messi and Argentina out for revenge after Copa controversy Best player in MLS? Zlatan wasn’t even the best player in LA! Having offered nothing of real note, Sanchez’s departure sparked a much-improved second-half performance from United which saw them come from behind for the first time under caretaker-boss Ole Gunnar Solskjaer.After United had caused early problems the visitors began to get on top and it was no real surprise when Southampton took the lead, even if the identity of the scorer was unpredictable. Given time and space to take down a Charlie Austin pass, Yan Valery unleashed a blistering 25-yard drive which David de Gea could only palm into the top of the net at his near post. Not a bad way for the 20-year-old right-back to score his first senior goal.At 1-0 down United looked short of ideas and options. Southampton defended in numbers and with structure, and while Lukaku struggled to find his touch Sanchez was far too anonymous once again.The Chilean drew a furious reaction from Solskjaer at one point, while Paul Pogba also threw his hands up in despair at the end of one faltering United attack.When Sanchez went down after losing a 50-50 with Jan Bednarek – jarring his right knee in the process – suddenly United’s fortunes changed.On came Diogo Dalot, whom Solskjaer had been preparing for some time, and the young Portuguese immediately made the kind of impact Sanchez had been unwilling or unable to make in the previous 52 minutes.Running directly at the heart of the Southampton attack, Dalot bent the visitors out of shape and teed up Andreas Pereira. The midfielder then took a touch and shifted the ball onto his right foot before delivering a beautiful curling finish into the top right-hand corner of the net.With the tempo suddenly raised, United were soon 2-1 up and swarming all over the Saints. Pereira’s charge forward made space on the left, and Lukaku held his nerve to slot home right-footed across Gunn.But just when it looked as though the Reds had a stranglehold a delicious free-kick from James Ward-Prowse went flying into the East Stand net and United were back to square one.But Lukaku was to have the last laugh in the 88th minute. On an afternoon which had shown him at his worst at times, he showed just how deadly he can be by pouncing on a loose ball and again steering home with his weaker right foot. For the second game running, Lukaku was the two-goal hero.There was still time for Paul Pogba to see an injury-time penalty saved by Gunn after Marcus Rashford had been fouled by Stuart Armstrong but by then the game was won.In many ways this was atypical of United under Solskjaer. Never had they previously experienced the tide going quite so back and forth. But in others this was the Norwegian’s reign in microcosm form.Injuries continue to stack up, question marks continue to be raised about the squad’s resilience, and Solskjaer continues to show he can deliver answers few considered him worthy of producing.The one glaring issue which remains for the manager is the form of Sanchez. Thankfully, he is finding ways to win despite the constant disappointments of the Chilean. Check out Goal’s Premier League 2019-20 fantasy football podcast for game tips, debate and rivalries.