For the second time in four days, the Reds trailed at half-time, only to haul themselves back into the game and snatch victory in the second period.
This time, at Southampton, it was Michael Owen and Javier Hernandez who did the damage, breaking Saints hearts after the home side had taken the lead on the stroke of half-time.
And, just as they did at Bloomfield Road on Tuesday night, Sir Alex’s substitutions made all the difference at St Mary’s. The Reds had been second best all over the pitch until the boss introduced Nani and Ryan Giggs just before the hour. Their presence, and a re-jigged formation, had an instant impact. Within seven minutes, United had levelled. After a further 11, the Reds had one foot in the fifth round draw courtesy of another ice-cool Javier Hernandez finish.
United's South Coast excursion may have yielded the same result as Tuesday’s trip to Blackpool, but the side was markedly different. Danish goalkeeper Anders Lindegaard was handed his United debut and played behind a Reds back four of John O’Shea, Chris Smalling, Jonny Evans and Fabio. Darron Gibson, Paul Scholes and Anderson were tasked with taking charge of midfield matters, while Gabriel Obertan and Hernandez spearheaded the attack, with Owen, somewhat surprisingly, playing in the hole.
Southampton boss Nigel Adkins also tweaked his side to give some of his younger squad members a taste of FA Cup action. Among those who benefitted was 23-year-old goalkeeper Barotsz Bialkowski, who came in for first-choice Kelvin Davis.