West Brom head coach Tony Pulis was left to rue Saido Berahino's second-half miss in the 2-0 Premier League defeat to Old Trafford on Saturday.
Jesse Lingard's first goal for the club put the home side ahead before Berahino, just moments after being introduced as a second-half substitute, headed over the crossbar when unmarked inside the six-yard box.
Juan Mata's late penalty sealed the win for Louis van Gaal's side and Pulis admits Berahino's chance could well have been the decisive moment.
"If you need a chance to drop to anyone - the gilt-edged chance - you're hoping it drops to Saido," Pulis said.
"He's missed a chance which could have got us something out of the game."
Gareth McAuley was sent off for the challenge on Anthony Martial which allowed Mata to score from the spot and Pulis accepted that referee Mike Dean had little alternative.
"It’s difficult for Mike," he said. "You could feel, with a couple of minutes to go, that he might look at it 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."
However, Pulis revealed some players had made it clear that James McClean was unlucky not to be awarded a spot-kick of his own after a touch from Phil Jones.
"I haven't seen it, but they say Jones has caught James McClean second half over on the far side," he added.
"He's actually taken his foot away from him, but I haven't seen it so I couldn't be definite on that."
West Brom are down to 13th in the table following the defeat and Stoke City's 1-0 win over Chelsea.
