The struggling Baggies were given a spot-kick almost immediately after the restart at Old Trafford after impressive Chelsea loanee Conor Gallagher appeared to be fouled by Bruno Fernandes inside the box.
However, referee David Coote then overruled his own decision after watching the incident back on the pitchside monitor, deciding that the Portuguese got a touch on the ball during his risky challenge.
West Brom’s misery was compounded just 10 minutes later, when, after a Darnell Furlong handball, Fernandes stepped up to net what proved to be the winning goal from the spot at the second attempt after former United goalkeeper Sam Johnstone had saved his first effort but was spotted coming some way off his line by the VAR, leading to a re-take.
Both Baggies boss Slaven Bilic and United counterpart Ole Gunnar Solskjaer expressed their frustration with the officials after the full-time whistle, while Red Devils legend Ferdinand - covering the match as a pundit on BT Sport - heavily criticised Coote’s decision-making.
“It’s a disgraceful decision, he got it right first time,” he said of the West Brom penalty incident.
"He’s gone there looking at it [the screen]. How do you actually go against the decision that you made initially when you’re looking at it again in slow-mo?
“The more you look at it, the more it’s a pen.”