Patrice Evra admits he is concerned by Manchester United's defending.
United required another thrilling late comeback just to snatch a 2-2 draw on Saturday as Sunderland came within 90 seconds of recording their first win at Old Trafford since 1968.
"I am worried that we are not keeping clean sheets," said Evra.
"I am not happy about it because if you want to win the league you have to keep clean sheets. Last year we only conceded 21 goals. We can't concede more than that this season."
Sunderland boss Steve Bruce, more than anyone, knows United can never be counted out until the final whistle.
After all, it was Bruce who scored those two late headers against Sheffield Wednesday in 1993 that had Ferguson dancing on the touchline and Brian Kidd on his knees saluting the heavens.
"I would love to see a stat of how many times they have scored to rescue a game in the last minute after they have not played well," reflected Bruce.
"They always seem to get something out of a game.
"That is the mark of champions. That is why they do what they do.
"At the top of that is the Ayatollah himself who sits and watches it. That is what he has brought to the football club. They never give in."