Cristiano Ronaldo and Bruno Fernandes fired Manchester United back into the top-four with a battling victory over 10-man Brighton & Hove Albion, who slipped to their second away defeat of the season.
Ronaldo ended his six-match goal drought with his ninth Premier League goal of the season to give United control after a flagging performance in the first half, before Fernandes fired home after a quick break in the dying embers of the match.
Brighton added to a woeful record at Old Trafford that has now seen 12 defeats and two draws, and will be frustrated with a period, shortly after the break, that saw a gifted goal followed by a red card to captain Lewis Dunk.
Six minutes after the break, Yves Bissouma's careless loss of possession gave Ronaldo scope to glide to the right and unleash a shot just inside the box, and past Robert Sanchez.
Moments later, Dunk brought down Anthony Elanga and was sent off having been adjudged to have prevented a goalscoring opportunity after a VAR review.
United will take solace in return to winning ways after successive draws to Burnley and Southampton hindered progress under interim head coach Ralf Rangnick.
After a formidable away record saw only one league defeat previously - to Aston Villa - Brighton will be disappointed by the manner of the uncharacteristic spell that proved detrimental to their efforts in Manchester.
Story of the match
Both sides had chances throughout the opening passage of play, with Brighton the team dictating possession and probing for an opener to aid a maiden victory at Old Trafford.
The robust Jakub Moder's energetic display was complimented with a first Premier League, if not for the imperious David De Gea's stretching save denying the Pole's thumping header.
After displaying their trademark fluidity resilience, Albion entered the break with optimism that the unwanted record at Old Trafford could be ended.
Robert Sanchez had a busy night in the Brighton net, acrobatically preventing a fierce Ronaldo header and redeeming a careless error with a fine save against Fernandes.
United are still not at their cohesive, ferocious best, but victory on Tuesday night certainly aids their prospects for the rest of the campaign, and appeases a hungry fanbase.
Jadon Sancho looked lively in attack and Harry Maguire and Victor Lindelof looked assured in defence, whilst De Gea's magnitude in-between the sticks was exemplified by another fine display.
Key takeaways
United ease worries over bid for top-four
United have been under intensifying pressure under Ralf Rangnick, but grabbed a vital victory against a resilient Brighton side and reaffirmed their claim for a spot in next season's Champions League.
It wasn't perfect, but the ability to grab a lead and maintain it has been something that has evaded United in times this season, and the squad will be galvanised by elements of the performance.
Lapse in concentration proves fatal
Graham Potter will have been incensed by his side's costly blunder, with Dunk's dismissal effectively nullifying the good work that had been on offer throughout the first half.
Despite this, Brighton continued their tenacious approach and came close through Moder's second half effort, deflected against the crossbar.
The result will sting for Albion after good work in the first half, and the snapping of a seven-match unbeaten run reminds the club that there is work still to be done for an improving side.
Next time out
Both teams return to Premier League action at the weekend, with Brighton hosting bottom club Burnley on Saturday and United travelling to fierce rivals Leeds United the following day, with hopes of strengthening their position in the top-four.