For a few weeks now this has been shaping up into one of the really great championship run-ins. But so many times over the years it has just taken one freak incident - a bad call or a shock goal against the run of play - to separate teams involved in the sort of head to head duel that we are seeing played out between Arsenal and Manchester United just now.

When David Elleray decided to award Liverpool a penalty last night for what looked like a perfectly good challenge on Oyvind Leonhardsen by Jesper Blomqvist, I couldn't help getting the feeling that we were seeing that one incident, the split second, that had turned the 1998/99 season in Arsene Wenger's favour.

Overall it wasn't a bad performance by Liverpool but, to be fair, for most of the game they were clearly second best. United, at this stage, barely even seem to take account of who they are playing. They go to a ground like Anfield and play their own game, allowing the opposition to try to cope as best they can.

Liverpool, quite simply, don't possess the sort of class that would enable them to genuinely handle a team of United's quality. Last night they battled hard but they still didn't deserve the break that they got in the 70th minute when they were rescued from what looked like a pretty much hopeless situation by a poor refereeing decision.

Blomqvist's tackle actually looked like one of the best of the night and yet it not only ended up leading to United's lead being halved, it undoubtedly handed Liverpool an opportunity to scrap their way back into the game. They seized that chance with both hands and so, with that one decision, Elleray changed the course of the game and, quite possibly, the season.

In fact the referee has dealt the Old Trafford club blows on two fronts, with the penalty decision representing a major blow to their league aspirations while the sending off of Denis Irwin - harsh though not as harsh as the penalty - will prevent the Irishman from playing at Wembley against Newcastle.

That's not to say that last night makes anything like clear-cut. United still have a game in hand and the goal difference is so close at this stage that it makes no real difference.

Just as Jamie Redknapp's penalty helped his side to take hold of last night's game, though, the combined impact of last night's results hands the initiative to Arsenal.

Their win at Tottenham last night was a huge win for them. To come out of the night two points better off than their rivals is important in itself, but the fact that Alex Ferguson's side had led 2-0 before eventually winning will be a huge boost to the defending champions.

On the face of it, Arsenal's game at Elland Road next week looks like an opportunity for them to really take control of the race, regardless of how United do at Middlesbrough. The Leeds defence is probably better than Liverpool's and David O'Leary's attack these days is more threatening than Gerard Houllier's, but with the home side having little to play for following last night's defeat by Chelsea, the leaders can drive their advantage home against the fourth placed team.

Certainly they will go there full of confidence. Few people who have watched the two leading contenders regularly this season could imagine Arsenal throwing away the advantage that United held over Liverpool last night, even if they had been unfortunate to concede a penalty with 20 minutes remaining.

Just now it seems as though the holders have that harder edge to their game. They are firmer at the back and scoring more goals and if they can maintain the sort of form they have shown in recent weeks next Tuesday, then it is difficult to see them slipping up in their last game at home to Aston Villa.

As for Chelsea and Leeds . . . well, you'd have to say that last night's win confirms the Londoners' claim to be part of a breakaway top three at the moment and they'll look back now at the recent draws against Leicester, Middlesbrough, Sheffield Wednesday and wonder might have been. The lack of a more regular goal-scorer cost them their shot at the title.

--(In an interview with Emmet Malone)