An outsider barely acquainted with the intricacies of football who wanted to know the key difference between Manchester United and Liverpool in the year 2000, as they prepare to meet in Manchester tomorrow lunchtime (Sky Sports 1), would do well to bear the following in mind.

Nine months ago, Liverpool went to Old Trafford having lost one of their previous nine games. They were to lose none of the next eight. It was a run that took them to second in the table. There was much talk of how Gerard Houllier was reforming the club.

They even took the lead at Old Trafford in March, when Patrick Berger lashed one in from about 25 yards. United actually seemed worried, and it was only when Ole Gunnar Solskjaer caught Sami Hyypia with a late tackle and then crossed the field to score, with Hyypia off the pitch, that parity was restored. The game ended 1-1.

Liverpool were buoyant. They may have been 10 points behind United in the league, but they had 12 games to go - 36 points to play for. Few expected Liverpool to mount a serious title challenge, but many were disappointed that they managed just 19 more points. They finished fourth.

United, meanwhile, had 11 games to play - 33 points. They got all 33. The difference between Manchester United and Liverpool is that United possess certainty.

Liverpool, still, do not, and an argument could be made for saying Houllier's side is less certain today than it was in March. Last Sunday's home defeat by Ipswich Town was their third in the league in the last four games, their fourth defeat in the last six. They trail United by 13 points.

Most telling for Houllier is the apparent subsidence in form of goalkeeper Sander Westerveld. His loss of confidence seems to have spread to the back four - Liverpool have conceded twice as many league goals as Leicester City this season - which is even more worrying when facing a United side with 44 Premiership goals already, in 17 matches.

Yet equally perturbing for Houllier is what is occurring at the other end. With Emile Heskey having scored 12 goals in his last 12 games, the battle to partner the former Leicester forward is becoming intense. It may even be turning ugly.

On Wednesday night Robbie Fowler was given the job initially, but his annoyance when substituted with 20 minutes remaining was clear. Fowler, who had tried constantly despite being out of form, shook his head as he walked past Houllier and Phil Thompson and continued to do so as he sat down behind them.

That Fowler was replaced by Michael Owen, who then scored the first goal against Fulham, can only have added to Fowler's growing sense of frustration. Fowler and Owen used to get on, but now there is resentment on Fowler's part that he has been eclipsed by his younger team-mate. Owen's formidable air of self-confidence hardly helps.

"I don't just say I'm the best because that is what's expected," said Owen, "I believe it. I have to because there is no other way at the top. I really believe in my ability and that I should be playing. I think everyone understands that desire."

Everyone except Fowler. He told his personal website: "I understand the manager's problem, but I also have to believe that I am the best." On Wednesday Fowler had felt compelled to repeat his allegiance to Liverpool and Houllier: "I've always said that I'm happy at Liverpool and that I want to stay here. We're going the right way under the manager and I believe it'll be sooner rather than later that we're picking up medals."

But either Fowler or Owen will be disappointed tomorrow and in the coming weeks. It is reasonable to assume that Liverpool would sell Fowler first.

Another Fowler denial this week concerned Liverpool's England players' relationship with their United counterparts. It was written that Fowler and some other Liverpool players had celebrated noisily as they watched their former team-mate, Steve McManaman, win at Old Trafford with Real Madrid. But Fowler's alibi is a good one. "You see, I was sitting in the directors' box using Alex Ferguson's season ticket, so I very much doubt if I would jump up there."

There seems little chance that Liverpool's directors will be doing so tomorrow. Tuesday will mark the second anniversary of the last time United were beaten at Old Trafford in the Premiership - they lost 32 to Middlesbrough - and with Ferguson stating that he wants United to remain dominant "through the ages" United will be keen to reinforce their superiority in this most bitter of fixtures.

"Liverpool have dropped some silly points and you can't afford to do that," said the normally quiet Paul Scholes, before adding the barb: "We always knew that Arsenal were our main threat anyway." Liverpool play Arsenal next Saturday.

Ferguson will hand Solskjaer a rare starting place because Dwight Yorke begins a three-match ban. "He's a terrific player," said Ferguson. "Ole has been unlucky this year and he'll have been a bit frustrated, but he'll figure a lot now. He's improving as a player and we expect him to get better. He'll get his chance now."

Ferguson is expected to bring back Scholes and Sheringham, who started on the bench against Charlton last Saturday, while goalkeeper Fabien Barthez has recovered from his ankle injury.