Chelsea's late-season surge continues and, despite Manchester United still heading them by six points, part of the message from Carlo Ancelotti's side is that Fernando Torres has finally scored, and may continue to do so until the title is decided.

The Spaniard's first goal since the second of a pair scored for Liverpool against Wolves in late January suggested his sharpness has returned. On the rain-soaked Stamford Bridge turf the ball held up behind the striker but he was able to nonchalantly pirouette before delivering the sweetest of finishes with his left foot, eight minutes after coming on.

Ancelotti said: "It was an important moment for him and for all the fans who waited for Fernando to score. It was a fantastic moment and now his future will be fantastic here, [at] this club, with his team-mates. The big problem was he came in to a new club and it was not easy to find a relationship with the new team-mates and the play. But now the bad moments have gone."

Asked if the goal was a relief, Ancelotti said: "Obviously for him. He needed to score to move from this moment. The next game for him will be really better. [The finish] was good movement, a fantastic goal."

Torres told ESPN: "It was not the beginning I was expecting when I signed, but it's not easy to go in January or February. I kept working and it's thanks to all my team-mates that I scored. There's less pressure for me now – now I can enjoy it. Today the pitch was not the best [due to heavy rain] to score the goal, but football is like this."

After Florent Malouda smashed home in added time to confirm a 3-0 win that was a touch unfair on West Ham, Ancelotti was asked of his team's ability to retain their title. He said: "We have less possibility because we are one game less [as] now there are just four games [and] the gap is the same [to Manchester United]. So it will be more difficult but we have to keep trying to believe."

West Ham had begun this game rooted to the bottom, two points off 17th, which for any player in the relegation dog-fight at this juncture of the season will appear a yawning margin. Avram Grant lined his side up in a 4-3-3 that matched Ancelotti's formation, and it was Chelsea who had the best of the chances during a first half that frustrated the Italian yet ended in the best way.

Throughout the opening period Ancelotti had been waving at his side to slide balls in behind Lars Jacobsen, the visiting right-back. After 43 minutes Chelsea finally received the message, and they took the lead.

Didier Drogba, who had been the focus of most of Ancelotti's glowering but would end the contest as its best performer, twisted a pass that released Ashley Cole into a gallop. This had the visiting rearguard desperate to regain ground but before they could manage any damage limitation, the England left-back zipped over a cross that allowed Frank Lampard to bury a finish beyond Robert Green for a lead that had been coming.

First up, Malouda had raced down the inside-right channel but unloaded a shot that Green parried with his body, as Chelsea began proving that they can switch tempo when required, which has not always been true this season. When Freddie Sears hacked a clearance away the ball went straight to Malouda. He ambled a couple of steps, then smacked a pass into Drogba's feet. An instant turn allowed the Ivorian to blaze a shot at Green that skidded across the wet surface before the keeper collected.

At this point West Ham appeared to have dug in for an attritional contest in which they would defend while Chelsea came at them in waves of blue. Yet from somewhere Grant's team found their mojo. Sears sprinted from halfway and dinked over a cross that had Jonathan Spector diving into a header that forced Petr Cech into a first save.

Then, after a Mark Noble corner, Sears backheeled from close range but Cole stopped the ball on the line, and Cech gathered.

For a frantic period before Torres's intervention the drenched pitch levelled the contest as Drogba and company hurtled forward, before West Ham subsequently went close themselves.

Drogba played in Lampard but the midfielder could not finish, then the striker appeared in West Ham's area but his chested control proved too heavy. A David Luiz 20-yard drive crashed off Green's crossbar but this presaged West Ham moving into their opponents' territory as Demba Ba stung Cech's hands, then Robbie Keane – on for Mark Noble – failed to finish.

While Grant said the knee injury Noble sustained could be serious, Ancelotti was unsure about the muscle problem that caused Michael Essien's removal.

Ancelotti now has to decide whether Torres will start in Chelsea's next outing, which is next Saturday when Tottenham Hotspur are the visitors to Stamford Bridge. "Considering the performance of Didier today, considering that Fernando scored, we have to try and put both together. We have one week to train and then I will make the decision," he said.

Grant could at least console himself that Scott Parker should return immediately, after the newly crowned Football Writers' Footballer of the Year missed this one with an achilles problem.

Of West Ham's hopes of avoiding the drop Grant said: "We need to do what we need to do." Yes, and quickly.

THE FANS' PLAYER RATINGS AND VERDICT

TRIZIA FIORELLINO, ChelseaSupportersGroup.net When Torres finally scored I thought the ground was going to collapse, the noise was so loud. We were pretty average and our play was pretty slow. When Lampard scored I thought the flood gates would open but it didn't happen, but it was party time all the way once Torres scored. We keep winning but I think we probably left our run two games too late.

The fan's player ratings Cech 8; Ivanovic 8, David Luiz 7, Terry 8, Cole 7; Essien 7 (Benayoun 57 7), Lampard 7, Mikel 7; Malouda 7, Drogba 9 (Torres 77 8), Kalou 6 (Anelka 70 6)

TIM CONLAN, Observer reader I never thought we would get anything out of this game, especially when I saw the line-up, but I thought we played quite well. Grant gambled at the end with effectively four forwards and we got caught with two late goals, but I thought the scoreline flattered Chelsea. I think we could still stay up with 39 points, but it's possible rather than probable. We could do with a point at City next week.

The fan's player ratings Green 7; Jacobsen 7, Gabbidon 8, Da Costa 7, Bridge 8; Hitzlsperger 6, Noble 6 (Keane 60 5), Spector 8; Sears 8 (Obinna 82 4), Cole 7 (Piquionne 79 5), Ba 6

To take part in the Fans' Verdict, email sport@observer.co.uk