Sir Alex Ferguson has cited Edwin van der Sar's uncharacteristic howler against West Brom as the prime example of Manchester United's problems this season.
Saturday was the third time United have tossed away a two-goal advantage, throwing away more precious points in the Premier League title race and wrecking their fragile confidence.
Ferguson is almost at a loss to explain what is going wrong.
But he believes Van der Sar inexplicably dropping Chris Brunt's cross at the feet of Somen Tchoyi to gift the Baggies their equaliser could be evidence the answer may be nothing more than bad luck.
"The mistake was uncanny," said Ferguson, ahead of the Champions League clash with Bursaspor. "Here is a player with 130 caps for Holland and the most fantastic career you could imagine and he makes a mistake like that.
"You cannot even criticise him because he doesn't deserve that. He is allowed to make one horrendous mistake in his life. It was at a time when we didn't need it of course, but it happens."