Sir Alex Ferguson claims "being a Geordie" may have contributed to Steve Bruce's exit from Sunderland.
Bruce, a former player under Ferguson at Old Trafford, left Sunderland on Wednesday and the United boss believes he fell foul of the ruthless Tyne v Wear competition.
Ferguson said: "Fans just don't have the patience any longer, just see what happened to Steve Bruce up in the north east where being a Geordie didn't help him. In that part of the world they are so passionate and committed to their football team. I think Brucie has suffered because of that but that's the kind of supporters we have these days - no patience."
He added: "He rebuilt a whole team and that requires a bit of patience from everyone, including Steve. I think Steve was realising himself that he was going to have to wait.
"There was a complete turnaround in the summer, they lost a few players in the - the boy [Jordan] Henderson, the boy [Asamoah] Gyan, Anton Ferdinand, and you need that time.
"I think losing to Newcastle earlier on in the season didn't help him either because of the way they are in that part of the world but he will be back, Steve.
"In general his managerial record is very good."
Martin O'Neill is expected to be named as Bruce's successor at Sunderland and Ferguson has no doubts the Ulsterman will make a positive impact.
He added: "Martin has a very good track record. The job he did at Villa Park was excellent, he did a great job at Celtic, he won the League Cup with Leicester so Martin has got the experience and track record to do well.
"If that's the job he's going to I'm sure he will do well."