Sir Alex Ferguson branded Manchester United's 2-2 draw with West Brom as "inexplicable".
Goals from Javier Hernandez and Nani in the first half put United in control. But after losing Ryan Giggs to a hamstring injury, the home side collapsed in a six-minute spell after the interval, with Patrice Evra scoring an own goal before Edwin van der Sar's calamitous mistake presented Somen Tchoyi with an open goal.
"It is an inexplicable result and obviously frustrating," said Ferguson, who left struggling striker Wayne Rooney on the bench. "I suppose there are two ways of looking at it. If we were in the middle of the league we could say we were still undefeated. For us it is not good enough."
United have now drawn five times this season, including three on the trot in the Premier League.
They have also tossed away two-goal advantages on three occasions, which cost them precious points today and against Everton, with Dimitar Berbatov coming to their rescue to snatch victory against Liverpool.
"Sometimes it is better to be one goal in front than two. You keep your focus a bit more," said Ferguson.
"But what can you say about their second goal? Edwin van der Sar has probably been playing for 25 years and he was probably in primary school the last time he made a mistake like that. You have to just wipe it off the slate."
As for Albion, they have already won at Arsenal this season and seem certain not to get dragged into a relegation fight.
"It was an afternoon of gifts," said Baggies boss Roberto Di Matteo.
"If Manchester United had got a third the game would probably have been over. But I thought it was a correct result. Every game has its own history, so I wasn't thinking about their results, but I just felt if we got one back, it might make them nervous."