Rio Ferdinand believes Manchester United will struggle to fight for the Premier League title if they sell goalkeeper David De Gea.
The Spaniard was not involved in Saturday's 1-0 victory over Tottenham Hotspur.
Boss Louis van Gaal admitted that the situation is not easy to handle and that Sergio Romero will continue in goal at least for the month of August.
"If Manchester United lose David De Gea they can forget about a title challenge," he wrote in his column for The Sun.
"A club like United cannot allow a keeper of De Gea's stature to leave because the transfer fee they receive from Real Madrid will not make up for missing out on major trophies.
"Should David choose to walk out the door next summer, when his contract expires, then so be it. But United don't need the cash and they can afford to be strong.
"I know De Gea well from my days playing with him at Old Trafford and he is too professional to throw the towel in and sulk.
"He might not like the decision, but it's not the biggest hardship in the world to have to play for Manchester United for another year."