Peter Snow's old swingometer would struggle to cope with the shift in power that may result from Chelsea's visit to Old Trafford on Sunday. A win for Manchester United would see them six points clear at the top of the Premiership and make it eight successive league victories. Defeat, obviously, would bring the two sides level. For all their flowing football in the Premiership this season - and some of it has been breathtaking - doubts as to their championship credentials would be brought into even sharper focus.

One man likely to come under particular scrutiny on Sunday will be Louis Saha. Having enjoyed a renaissance that Raphael would be jealous of since Ruud van Nistelrooy's departure, the Frenchman has fully justified Sir Alex Ferguson's faith in him; the United attack has looked smoother and a much better collective unit with him at its hub. But Saha's inability to put away two glaring opportunities against Celtic - one of them a penalty - have raised questions as to whether he can deliver when needed most. Gary Neville is reported to have predicted that Saha would miss from 12 yards, apparently telling opponent Neil Lennon that Saha's "head has gone". It is a report that, significantly, Neville has not denied.

Of course, Saha may not see all that much of the ball on Sunday. This is a fixture that has more than a touch of the draw about it. United, with an eye on preserving their lead at the top of the table, may well curb their attacking instincts, while Chelsea would be happy going into a long hard winter just three points off the lead with a far deeper squad than United.

If the game does come down to a battle of attrition then, it will be a battle that suits Chelsea. Claude Makelele's combination of craft and bustle is ideally suited for a tight game in midfield. More significantly, he is a far better player than Lennon, who enjoyed such success breaking up United's play on Tuesday. Jose Mourinho will also be able to call on far greater reserves of strength should the game start to stagnate. As the match began to slip away from United on Tuesday, Ferguson had to resort to bringing on the less-than-stellar attacking talents of Patrice Evra and John O'Shea.

Last month's demolition of Bolton showed that United's best way to deal with a strong opponent is to play their natural game. Concerns about Saha aside - and he has been brilliant more often than been banal this season - United would do well to stick to their Plan A on Sunday: attack, attack and then attack some more.