For Manchester United, another game ticked off. Sir Alex Ferguson's men twice had to come from behind but this is the resilience that is taking them to their 20th league championship and, in that context, they will not mind too much that their late, dramatic search for a winner could not concoct a decisive goal.

The damage is only superficial when a team have their advantage at the top of the league and, though the gap is trimmed to 13 points to Manchester City, everything still points to the game at Arsenal on Sunday week as the moment when they can confirm the handover. For Robin van Persie, the scorer of their 77th-minute equaliser, it must be a sweet prospect.

Van Persie had been offside for his goal and Sam Allardyce lamented at some length afterwards about the injustice his team has suffered. West Ham United took the lead in the 17th minute when Ricardo Vaz Tê finished a move that had begun on the edge of their own penalty area and the goal from Mohamed Diamé, 10 minutes into the second half, was one of the outstanding moments Upton Park has witnessed this season. In between, Antonio Valencia had scored his first goal of the season but the champions-elect had looked flat for long spells, with Wayne Rooney enduring a difficult and undistinguished night, and it was only after Van Persie's goal that West Ham suddenly looked vulnerable. Allardyce can complain too often about match officials but on this occasion he had a point.

The West Ham manager was not alone, though, in harbouring a few grievances, Ferguson arguing that Andy Carroll deserved an "obvious red card" for the flying leap into David de Gea that poleaxed the goalkeeper in the first half. Carroll had been a difficult opponent for the league leaders, particularly in the opening hour, when it was not just his size that the opposition defence found awkward to handle but his movement and ability to bring others into the game.

He was booked in the second half for a far more innocuous tussle with De Gea but the way the Spaniard handled the earlier battering was another reflection of United's durability this season. De Gea may not have suffered a more crashing challenge since arriving in England, even going back to those periods when opposition teams would routinely try to rough him up. Yet the Spaniard is no soft touch these days and it was telling how Ferguson's players did not feel it necessary to back him up when he gave a little back in the second half. De Gea can fight his own battles now.

Ferguson, however, was entitled to object and it was difficult afterwards to know which manager was the most annoyed. Both had legitimate grievances but Allardyce was right to say the lack of offside against Van Persie had the greater consequences. Kagawa's shot had flicked off James Collins and ricocheted off one post to the other. Van Persie turned in the loose ball, putting away a finish that was probably harder than he made it look, but it was an unmistakably bad call from the assistant referee. Allardyce described it as an "easy decision".

West Ham had to repel some concerted pressure for the remainder of the match, Ferguson's players passing the ball with greater speed and penetration. Yet the lingering memory will be what happened in the 55thminute after Vaz Tê and Guy Demel worked a little passing triangle with Diamé near the right-hand corner of the penalty area. The turn from Diamé to spin away from Rooney was wonderful in its own right. The curling left-foot shot, struck with equal measures of power and precision, made it a goal of sumptuous quality.

Vaz Tê's goal had not been too shabby either. This time, Rooney misplaced a pass on the edge of West Ham's penalty area. Diamé carried the ball forward then played it to the left for Matt Jarvis. Rio Ferdinand was turned far too easily and, when the cross was chipped up to the far post, Carroll had a clear height advantage over Patrice Evra. Vaz Tê had anticipated that Carroll's effort might come his way and applied the decisive touch with a stooping header. Rooney, unwittingly involved in both West Ham goals, looked forlorn when he was substituted and will remember the occasion with little fondness.

Ferguson's men had flickered only sporadically before an equaliser that was classy in its creation. Van Persie's pass sent Kagawa running through the inside-left channel. Winston Reid dived in too impulsively and Kagawa dropped his shoulder, turned to the byline then played the ball across the goalmouth to precisely where Valencia wanted it. From two yards, Valencia could hardly miss.