Video: Tony Pulis on West Brom defeat

Which makes Berahino's miss at 1-0 with 15 minutes to go even more galling for the head coach, who had brought him on just five minutes previously.

The striker somehow ballooned an unmarked header from just six yards out over the bar. It was, by far, the best chance of the game at Old Trafford.

Pulis said afterwards: "If you need a chance to drop to anyone - the gilt-edged chance - you're hoping it drops to Saido.

"He's missed a chance which could have got us something out of the game."

Earlier on, United's Jesse Lingard had given Louis van Gaal's men the lead with a curling finish into the far corner.

Albion had defended heroically up until then, but Pulis was unhappy with his side's positioning for the goal.

He said: "The first goal was a poor goal for us to concede. We've got three people in between the goal.

"Then (Claudio) Yacob decides to join that line which has left Lingard on the edge of the box and he didn't really need to do that.

"It's a poor header from Chris Brunt, but if Yacob actually comes across with the midfield players then he would have picked it up.

"It's always small margins. Against the best teams they punish you."

Although Albion huffed and puffed, they couldn't create another chance as good as Berahino's.

Juan Mata then wrapped the game up for United with a 90th minute penalty, after Gareth McAuley chopped down Anthony Martial in the box.

Worse still for Albion, referee Mike Dean showed McAuley a straight red card and so will miss three upcoming games.

Pulis said: "It's difficult for Mike. You could look at with a couple of minutes to go that he might look at differently.

"But the letter of the law says that if he's last man and he brings him down he has to send him off."

Albion had their own penalty appeal waved away earlier on in the half, with Pulis adding: "I haven't seen it.

"He's actually taken his foot away from him, but I haven't seen it so I couldn't be definite on that."