Sam Allardyce could not contain his delight after his West Ham United side scored a sensational 3-1 Barclays Premier League victory over Chelsea.

The Hammers went in a Juan Mata goal down at half-time but, following two half-time changes from Big Sam, roared back to win through goals from Carlton Cole, Mohamed Diame and Modibo Maiga.

The noise inside a packed Boleyn Ground grew with every passing minute of the second half as West Ham produced a truly irresistible performance full of pace, power and tempo that the Blues simply could not handle.

"It has ended up being an unbelievable game," Big Sam told West Ham TV. "After a reasonably comfortable opening 12 or 13 minutes, all of a sudden Chelsea went 'bang' and scored. With the quality of players that they have got, Fernando Torres made the run and cut it back to Mata and his finish was superb. I could criticise the defenders but the quality of their play was so good that it got them in front.

"With them having two clean sheets in their first two games under Rafa Benitez, I thought it would be a test for us. We seemed to lose our way and our belief after their goal so, for me, it was about hanging on until half-time and then making some changes.

"At half-time it was aboue re-motivating the lads and re-establishing that if they do things the right way, they will get a lot of pressure on Chelsea and exposing their defence a lot more than we had done. We did feel their defence was a weakness and has been, even though Rafa had put it right in their past two games.

"Certainly we proved it to be a weakness because the quality of ball up to Carlton Cole and the quality of balls put in by Matt Taylor and Matt Jarvis and then Mo Diame picking the ball up and running at them put a relentless amount of pressure on Chelsea and they ultimately cracked in the end. That was magnificent for us."

Having got back on level terms through Cole's superb header, West Ham then escaped as Jussi Jaaskelainen made two fine saves and Mata saw his free-kick cannon back into play off the inside of the post.

After weathering the Blues' brief storm, the Hammers saw Winston Reid's header cleared off the line by Ashley Cole before going ahead when Diame buried Cole's lay-off. Then, in the first minute of added-time, Maiga finished with aplomb after fellow substitute Taylor had seen his shot pushed out by Petr Cech.

Big Sam paid tribute to his players, not only for their attitude and belief, but for the outstanding fitness they showed in pounding Chelsea into submission during the final 15 minutes.

"Of course, the quality of their team, they upped their game and came back at 1-1 and we needed Jussi to make some outstanding saves for us, then we got a bit of luck off the post.

"We were so great at the end and our fitness levels were so high that, for me, we ran Chelsea into the ground. To consider that was our third big game in six days, to produce that much energy at the end was magnificent.

"The reward we got was the win and it was an outstanding victory."

Big Sam was in awe of the performance of striker Cole, who returned to the starting XI in place of the injured Andy Carroll and produced one of his finest performances against the club where he started his career.

"Playing against Chelsea was always going to motivate him because he's a great lad. He has been patient and I've really enjoyed working with Carlton since I've been here. He's done a great job for himself and for everybody today - certainly for the fans - to send everybody home happy.

"He showed a lot strength for the first goal and great hold-up play, because that is what you need in the Premier League to build sustained attacks. Your front men have to play well and he played ever so well today.

"That was backed up by Diame, Taylor, Jarvis and Nolan and Noble got better. The defenders didn't have as much pressure on them, so when they needed to defend they did well. In the end, you can't say we can't deny we deserved the win."

The one damp squib on an otherwise perfect day was the news that Andy Carroll will spend a period on the side-lines after suffering a knee injury at Manchester United in mid-week.

"It's a lateral ligament strain, which is the outside ligament running down the knee. It's a mid-term injury in that it could have been a lot worse and it could have been easier. We feel it'll be six to eight weeks. He's in a knee brace and doesn't need an operation, which is a good thing, and hopefully he'll be back with us very soon.

"With Andy and the other players, we do need them back quickly because we've got a lot of trauma injuries - Vaz Te's shoulder, George McCartney's ankle and Yossi Benayoun. We also haven't seen much of Alou Diarra or Jack Collison this season.

"We're suffering at the minute and to suffer like that and beat Chelsea 3-1 means I can't stop smiling!"