Manchester United might not win the Premier League title again for another decade, according to former England international Danny Mills.
The current champions suffered a 3-0 defeat by Liverpool on Sunday and are seventh in the table, 18 points behind leaders Chelsea.
"It could be 10 years at least before they win the title again," Mills told BBC's Match of the Day 3.
"The whole rebuilding process is going to take three or four years at least."
He added: "Then you have got to think Manchester City, Chelsea, Liverpool will strengthen - and Tottenham and Arsenal could possibly strengthen as well."
United won the title by 11 points last season, but since David Moyes replaced Sir Alex Ferguson as manager last summer they have struggled.
Aside from being out of the title race, the Old Trafford club are also 12 points off one of the top four spots needed to qualify for next season's Champions League. They have only missed one season of European football's premier competition since 1993-94.
United could still qualify for the Champions League by winning this season's competition. But the club will have to overturn a 2-0 deficit against Olympiakos on Wednesday to stay in the tournament.
"David Moyes has not won the league. He has not won a trophy," added Mills.
"If he had a good team he might get back in the top four and Champions League, but I think that they are a long way off competing and winning the title.
"Going into Manchester United, you had to build on massive success and that is where David Moyes has found it difficult."
United striker Robin van Persie scored 26 league goals last season, but has scored just 11 so far in the current campaign.
"Van Persie doesn't look like he wants to be there and wants to leave," said Mills.
"You look at his body language and he doesn't look happy there does he? Something is not right with him."
Fellow BBC Sport pundit Kevin Kilbane, who played under Moyes at Everton, believes not being in the Champions League would hurt United, but that his former manager needs time to turn around the club's fortunes.
"The game against Liverpool probably highlighted how far they have fallen behind the top four or five teams in the Premier League," he said.
"It is going to take a little bit of time for Moyes to adjust into that job. He's finding it difficult right now and Liverpool really exposed them.
"This transitional period could take a few years before they really get the signings that Moyes wants to get in."
United's struggles come after a period of domination of the English game during which they won 13 league titles during Ferguson's 26-year reign.
And they will want to avoid the sort of decline which has seen Liverpool fail to claim a top-flight title since 1990 after they led the way during the 1970s and 1980s.
The Anfield side are second in the league and four points off Chelsea with a game in hand as they challenge for this season's title.
"The defence is Liverpool's weak point, but in midfield and up front they are as good as anything around in Europe and certainly in the Premier League," added Kilbane.