Frederic Kanoute turned up like the penalty box poacher he is to rescue West Ham's FA Cup ambitions at a passionate Stamford Bridge.

The Hammers striker conjured the equaliser with just eight minutes remaining in a match during which West Ham rarely looked like doing anything other than taking a knockout punch.

Chelsea boss Claudio Ranieri must have left Stamford Bridge scratching his head over how his men can be so brilliant one minute and so ordinary the next.

Indeed, Chelsea are a bit like the nursery rhyme. When they are good they are very, very good, when they are bad they are horrid.

In the first half they were quite magnificent. In the second their long-suffering fans must have had their nerves shredded as first West Ham came back into the game and then at the end threatened to snatch it.

That would have been a gross injustice, for rarely can a player have given a more comprehensive display of the striking art than Jimmy Floyd Hasselbaink, who directed proceedings in this typically rumbustious London derby with stirring panache.

It might be going too far to claim this was a one-man show by Hasselbaink but such was his terrorising influence on the West Ham defence for the 75 minutes he was involved that it wasn't far from it.

Indeed the exquisite skill with which the Dutch striker set the tone with the first goal after 21 minutes was worth the admission money alone on an afternoon when Stamford Bridge was sprinkled with empty seats. Can it be the FA Cup is losing its magic after all?

Surely not with the likes of Hasselbaink around. When he picked up the ball 40 yards out on the left touchline there seemed to be no danger. As he slipped the ball onto his left-foot, however, the West Ham defence backed off and backed off with dangerous complacency, considering Hasselbaink is hardly the sort of striker who needs a second invitation to shoot.

On most occasions he might have unleashed one of those venomous drives for which he is famous. Not on Saturday. Instead he laid open his body one way and clipped the ball with his left foot the other and the arc with which it sailed into the top right corner of West Ham's net was such that even from the edge of the area goalkeeper David James barely moved.

It might not quite have ranked with the wonder goal with which Gianfranco Zola clinched the third round replay against Norwich but it wasn't far away on an afternoon which threatened to cement Chelsea's superiority over their London rivals.

It wasn't just Hasselbaink's striking prowess, however, which marked out his performance as special. It was his superb link-up play, the way he acted as provider for the likes of Zola and fellow-striker Mikael Forssell, the latter being guilty of wasting two chances in the first-half courtesy of Hasselbaink's work which the Dutchman would surely have converted.

As it was Hasselbaink, who gave way to Sam Dalla Bona in the 75th minute with what looked like a leg strain might have had a hat-trick himself by half-time in a match in which the Blues for long periods were back to the form which beat the Hammers 5-1 at Stamford Bridge only last Sunday, rather than the side which surrendered humiliatingly to Tottenham in the Worthington Cup in midweek.

Spare a thought, however, for Ranieri who must be as perplexed as everyone by his side's wildly fluctuating form.

But also spare a thought for West Ham's boss Glenn Roeder, who saw his side completely outclassed in that first half but then stirred them into a comeback which was as spirited as it was courageous.

It has to be said West Ham were again transformed as an attacking force by the introduction of Jermain Defoe, who came on in the 65th minute for Rangvald Soma and immediately asked questions of the Chelsea defence.

He might well have pinched the equaliser himself if he had not been unceremoniously hauled down by John Terry.

But together with Kanoute he led the rally which eventually bore fruit when Michael Carrick took a free-kick on the left side of the penalty area.

The ball fizzed across the box before landing at the feet of Kanoute, who swivelled in one movement and dispatched the ball past Chelsea goalkeeper Carlo Cudicini.

West Ham probably just deserved their replay for their brave rally though Ranieri would hardly agree.

It used to be from match to match that the Chelsea boss didn't know how his side would perform. After this he can't tell from one half to the next.

Teams:

Chelsea: Cudicini, Ferrer, Desailly, Terry, Melchiot, Zola, Lampard, Petit (Jokanovic 82), Le Saux, Forssell (Gudjohnsen 70), Hasselbaink (Dalla Bona 74).

Subs Not Used: de Goey, Morris.

Booked: Lampard, Terry, Ferrer.

Goals: Hasselbaink 21.

West Ham: James, Repka, Dailly, Schemmel, Winterburn (Labant 76), Hutchison (Lomas 68), Carrick, Soma (Defoe 65), Cole, Di Canio, Kanoute.

Subs Not Used: Andersson, Kitson.

Booked: Hutchison, Repka.

Goals: Kanoute 83.

Att: 33,443

Ref: D Elleray (Harrow-on-the-Hill).