As expected a spirited Southampton side pushed United all the way, but it was Robin Van Persie that made the difference as the Dutch striker hit his first Manchester United hat trick to give his side a somewhat underserved 3 points.
Lambert gave Southampton the lead on 16 minutes after he climbed above Rafael to nod past Anders Lindegaard but Van Persie elegantly pulled United level converting from an Antonio Valencia cross.
Southampton took the lead again when Schneiderlin capitalised on Patrice Evra’s slip in the box to head past Lindegaard on 56 minutes, and they proceeded to make the game even tougher for United, setting up to nullify everything United threw at them.
United caught a break and had the chance to pull level after Van Persie was scythed down in the box, but his chipped penalty was saved.
It looked like it wouldn’t be United’s day and Southampton would ruin Sir Alex’s celebrations but United weren’t ready to give up just yet.
Van Persie made amends bundling over from close range after Rio Ferdinand’s header hit the post on the 87th minute and then 2 minutes into 4 of injury time Nani’s corner was nodded in by Van Persie to complete his hat trick and complete United’s comeback.
The goal was also Van Persie’s 100th Premier League goal and I don’t think United fans will have ever been happier to see him celebrating.