It was September 2002 when Sir Alex Ferguson delivered what is probably – behind that epic night in Barcelona when "football, bloody hell" became a part of our football lives – the most instantly recognisable quote of his time as Manchester United's manager.

His team were going through one of those spells when it felt as though the roof at Old Trafford could tumble in. They had finished the previous season 10 points behind Arsenal and barely a month into the new campaign they were six points down on Arsène Wenger's side. Alan Hansen, the man who once said you don't win anything with kids, had described Ferguson's position as "the greatest challenge of his career".

The response was delivered like a cobra strike, quick and brutal. "My greatest challenge was knocking Liverpool right off their fucking perch," Ferguson said. "And you can print that."

Liverpool's last league title was in 1990, and Ferguson did not win the first of his 11 championships until three years later. In between, Arsenal and Leeds United both won the league. Yet everyone knows what Ferguson was talking about and, for Liverpool, the bare facts are that it could conceivably get worse before it gets better.

Forget, for one moment, all that stuff about United not playing well. The simple fact is that apart from one night, in November in the Carling Cup at West Ham, they have not lost a single match. Everything seems to be falling into shape and unless something can happen to stop their current trajectory it is difficult to see beyond them winning the title that would establish them as the most successful league side in the history of English football, with 19 championships compared to Liverpool's 18.

That statement is made with a slight note of caution because it is true that United have not totally clicked. They have won matches without finding the cohesion which we tend to expect of them and it was the same again as they maintained their superiority over a disjointed Liverpool at Old Trafford. Ferguson's men did not get on top until Steven Gerrard was sent off and even then there was never any sense they would overwhelm a side languishing four points above the Premier League's relegation zone and now missing their best player. The Old Trafford crowd was crowing and jubilant, but not exhilarated. They were efficient rather than exceptional.

Yet what we are seeing are a team of serial winners playing with no trepidation and demonstrating the kind of belief that takes years to cultivate. It is a mentality, a combination of know-how and "seen-it-all-before" expertise, as well as knowing how to handle the various issues and problems that can threaten a season.

You go through some of their players individually and wonder what all the fuss has been about. Rio Ferdinand, for example, was probably the best player on the pitch, when it was not so long ago people were wondering whether he might be finished. Michael Carrick and Darren Fletcher have been coaxed out of dips in form. Jonny Evans's confidence appears to have been rebuilt behind the scenes. Rafael da Silva has been taught how to defend. Dimitar Berbatov is a far better player than he was a year ago. Nani is improving at an even faster rate, with 38 goals or assists in 40 appearances.

The only problem yet to be solved is Wayne Rooney's lack of goals – he has only three so far, compared to 34 last season. Yet even that has not made a significant impact and, once again, it is a testament to the ethos that comes from Ferguson. Rooney might have played like a drain at times, but others have stepped forward. United have had 18 different scorersand it would have been 19 if Evans's header in first-half stoppage-time had not come back off the post.

You look for weaknesses and there aren't many. Gary Neville, at 35, is one, but he has been taken out of the squad since his display at West Bromwich Albion on New Year's Day. The goals will surely come for Rooney, who should be back for Sunday's game at Tottenham Hotspur. Nemanja Vidic should also be fit, Ferguson reported, and Tomasz Kuszczak has done well enough in goal in the last three games to mean it will not be too drastic if Edwin van der Sar misses out again.

Being knocked out of the FA Cup will have hurt Liverpool considerably but it is what happens next that might bring the worst pain.