Manchester United manager Sir Alex Ferguson has admitted he could have signed Edwin Van der Sar in 1999 but the club opted for Mark Bosnich instead.
The 38-year-old eventually joined United in June 2005 and has since gone on to win two Premier League titles, a League Cup and the Uefa Champions League title.
The former Fulham stopper recently broke Chelsea keeper Petr Cech's Premier League record for the most minutes without conceding a league goal while also setting a new record for the most consecutive games without conceding which currently stands at 11.
At the time Ferguson was on the lookout to sign a replacement for the recently retired Peter Schmeichel but admits that before he could act the club had done a deal for Bosnich.
The Australian endured a turbulent second spell at Old Trafford, after being released as a youngster in 1992, and was sold to Chelsea in 2001.
"There is no doubt about it, it was a mistake not signing Edwin in 1999," the Scot admitted.
"I did want him, but at the time (former chairman) Martin Edwards had done a deal with Mark Bosnich and unfortunately, it was too late because Edwin went to Juventus instead.
"But throughout the 2004/05 season we were assessing where we should be going in terms if the goalkeeping situation and I left it to out goalkeeping coach, Tony Coton, to get all the information.
"A lot of goalkeepers were a possibility but Van der Sar's name just came up all the time, so we didn't hesitate at the end of the season. We did a deal quickly.
"For Edwin, it was a great lift for him, but also for us. He has brought incredible knowledge and patience to the back four.
"His use of the ball is excellent and he has all the technical attributes you need."
United can go five points clear at the top of the table with a win at home to Everton on Saturday with title rivals Liverpool and Chelsea battling it out at Anfield on Sunday, but the 67-year-old is aware of the threat the Toffees pose.
"Only one thing is inevitable in this league and that is that it is full of shocks," he added.
"We have lost leagues on the final day and won them on the final day, so we are treating this seriously, no matter who we play.
"David Moyes has done an incredible job at Everton without getting the credit that he deserves. He has never had the resources that you get at a club like United."