Jussi Jaaskelainen insists fellow shot-stopper Edwin van der Sar is still one of the best goalkeepers in the world and should continue playing whilst he is at the highest level.
The Dutchman announced he is to quit Old Trafford and retire at the end of this season.
However the Bolton Wanderers number one believes van der Sar still has what it takes to steer Manchester United to further glory and says the Red Devils may struggle to find a world-class replacement.
The Finnish ace is also sad that Saturday's Premier League encounter between United and Bolton could be the last time he lines up against van der Sar if they do not meet in the FA Cup final.
"He is still at the top of his game and is still in the top three players in our position anywhere," the 35-year-old said.
"I am sure Manchester United do not want him to retire, even though he is 40 now, because he is so important for them.
"You saw when Peter Schmeichel was there it took them a few years to find someone who was at the same level.
"The Premier League is not the easiest league to come into as a 'keeper.
"You have seen many not do so well.
"Alex Ferguson has said that he wished he'd found him five years before, so it is going to be hard to replace him.
"I am almost 36 but I'd never retire while I can play at the highest level."