Sir Alex Ferguson could miss the start of next season as he will go into hospital over the summer for a hip operation.
The Manchester United manager is booked in to have surgery after the club's pre-season tour at the end of July, which includes visits to Thailand, Australia, Japan and Hong Kong.
United's domestic season starts with the Community Shield at Wembley on August 11, against either Manchester City or Wigan, with the Premier League starting the following weekend.
No timescale is being placed on the likely length of Ferguson's absence but it would need a very quick recovery for him to be back in the dugout in time for the start of the season.
The Scotsman has always said that his health would dictate how long he stays in charge at Old Trafford and he was taken ill at a function in Scotland last summer, his nosebleeds being put down to the number of short flights he had undertaken.
He had to miss United's pre-season matches in Norway and Germany and also sat out a mid-winter break in Qatar.
But that did nothing to dim his passion as he guided United to their 13th Premier League title, and he was in rude health on Friday as he poured out champagne to reporters at his Carrington press conference.