United simply had to avoid defeat to keep the title race mathematically alive, but a late header from Jay Rodriguez gave West Brom a hugely surprising three points and finally gave their fans something to cheer this season.
More importantly, though, it means Pep Guardiola’s City team cannot now be caught at the top of the table, thus handing the Catalan coach his first Premier League crown in just his second year in English football.
Realistically it was always a matter of when and not if City would become English champions for a fifth time following a dominant season from the blue half of Manchester.
But, just a week after spoiling City’s title party by beating their local rivals 3-2 at the Etihad, the way United abjectly gifted the title to their neighbours will sting.
United’s comeback at the Etihad from a 2-0 half-time deficit offered their supporters a rare fillip of flair and excitement after a difficult season where their style of play has hardly endeared Jose Mourinho to the club’s fanbase.
And that was also the case on Sunday, as United failed to spark the imagination in any tangible way even though they were playing a side that had hadn’t won in the league since January.
West Brom sacked manager Alan Pardew at the start of April after just four months following one win in his 18 matches in charge, but even a famous win at Old Trafford may be too little, too late for the Baggies as they still lie nine points off safety with just four games remaining.
United dominated possession early on, but despite the efforts of Romelu Lukaku and Alexis Sanchez, precious little real impact was made by the home side.
Lukaku saw one shot cannon back off the face of West Brom goalkeeper Ben Foster, while Pogba’s desire to make a difference saw him booked after half an hour for attempting to steer the ball into the net with a very obvious, very deliberate handball.
Prompted by the abject nature of the opening 45 minutes, Mourinho brought on Jesse Lingard at half-time and he was immediately in the heart of the action as United attempted to wake from their slumber.
West Brom, to their credit, also kept probing forward but they lacked the class required to really open United up at the back.
Mourinho attempted to end the stalemate – and the tedium – by introducing Anthony Martial with half an hour remaining and his introduction undoubtedly lifted the quiet Old Trafford atmosphere.
Increasingly poor conditions and a general lack of thrust continued to inhibit both sides, but United did force Foster into wonderfully save on 66 minutes when he tipped a Lukaku effort around the post.
However, the plucky visitors then sensationally seized their chance when Chris Brunt delivered a corner from the right with 17 minutes remaining. Nemanja Matic panicked at the delivery and headed back inside to Rodriguez, who could not miss from three yards out.
United, sensing the impact of the result, threw everything forward but West Brom displayed some new-found defensive fortitude and held on for a famous victory.
United will want to forget the result and its significance as quickly as they can.
However, the fans of West Brom — and certainly Manchester City — are likely to remember it for quite some time.