Sir Alex Ferguson believes Chelsea will be the greatest threat to Manchester United for the Premier League title next season, provided Jose Mourinho returns to his former side.
The United manager is on course to win a 20th league title with the Red Devils, currently 15 points clear of holders Manchester City, and he has the opportunity to put further daylight between the Red Devils and their bitter rivals when they clash in the derby on Monday night at Old Trafford.
Although United are coasting to this year's championship, Ferguson has warned his team will not ease up next season. "We've got a lot of youth in the team, there's no doubt about that," he said. "The record over the last 20 years tells you we're not going away. So I'd expect us without doubt to have a real good challenge next year."
While the Scot is confident of United being in the title tussle, the 71-year-old feels Chelsea will be right in contention, dependent on whether Mourinho decides to come back to Stamford Bridge. Ferguson's failure to mention Liverpool is perhaps a sign he believes Brendan Rodgers will not be able to conjure up a challenge from Merseyside.
"You'd expect - if Jose goes back to Chelsea - a big challenge there," Ferguson said. "[Manchester] City won't go away, with the money they've got. And I think Arsenal will improve - there's some indication that Arsenal are building a better squad than people think and Tottenham have been progressing for a couple of years now.
"So it's a hard league to win, there's no doubt about that. But at this moment in time we just need to concentrate on winning the league this year."
Mourinho was in charge of Chelsea for four seasons, with the Portuguese delivering Premier League titles in his first two campaigns and lifting four more trophies during his tenure.
The man who has so often been tipped to replace Ferguson at United guided Real Madrid to the Primera Liga last season as they toppled Barcelona, but a fallout with the club's hierarchy and reported unrest in the dressing room make his departure from the Bernabeu likely come the end of the season.