Gianfranco Zola admitted Manchester United's first goal had all but ended his side's challenge at Old Trafford on Tuesday.
The Hammers had held firm for the opening 37 minutes, going close to opening the scoring themselves through Valon Behrami and Alessandro Diamanti, only for Wayne Rooney to break the deadlock with a scintillating goal of his own.
Substitute Ji-Sung Park and Dimitar Berbatov combined before Rooney clinically headed in Antonio Valencia's sensational volleyed cross to complete a flowing one-touch move.
"To be honest their first goal was a very good one," said Zola. "It was well manufactured, although it was really unusual to see Manchester United score on the counterattack at home.
"After that, I was expecting more but it's not easy to play against Manchester United when you're one-nil down. They don't make it easy for you to come back but we've got no excuses."
After falling a goal behind, the Hammers' challenge waned as the reigning Barclays Premier League champions celebrated Old Trafford's 100th birthday with a much-improved second-half display.
Just 12 seconds had elapsed when Valencia found Park inside the box and the South Korean rattled the underside of Robert Green's crossbar with a rising drive.
While the visitors continued to try and pass the ball through United's midfield, the lively Valencia, Darron Gibson and Paul Scholes began to exert more and more influence as the game wore on.
"I'm not very pleased to be honest. I think that we were OK until they scored the first goal and, after that, we should've done more.
"In the first half we did very well coming from the back and playing through the midfield, but we didn't do as well as we normally do up front. Guillermo Franco and Carlton Cole couldn't control the ball properly and it was different.
"I liked the way that we occupied the pitch in the first half. We showed composure and played some good football. I take that as a positive but, to be honest, I'm expecting a lot more from my team."
With eleven days before the vital home match with Bolton Wanderers, Zola wants his players to regain their best form - both mentally and physically - as quickly as possible.
"We have to do much better than this and refocus straightaway because an important game for us is coming up next week, it's as simple as that."
One man Zola and his players will be happy to see the back of is Rooney, who took his goal tally to 23 in 27 league appearances with two textbook headers.
"I described Wayne Rooney as a King Midas. Everything he touches now turns into gold. He's in the type of form where every opportunity can turn up a goal. I thought he had a normal game tonight but he still scored two goals and could've got another one. That says a lot about the player.
"Having a player obviously helps the situation but, don't forget, one player cannot do everything on his own. He can certainly make a big difference to the team that's got him, although there have to be other players supporting him. Manchester United and England both have those players so they will be successful."
With the spectre of Rooney now a thing of the past Zola, who confirmed that influential midfielder Scott Parker had been rested due to tightness in his muscles, is expecting an improved performance - and result - against the Trotters.
"I though that Tuesday was a fantastic opportunity for us because in our previous two matches we built up a good platform to go there and play with more freedom, without being under too much pressure. I was expecting to be more positive but, honestly, it's easy to say that from the outside but when you're out there against the champions it's not so easy.
"I think that, generally, we've been playing better recently and that's given us greater confidence. Forgetting about Tuesday, I think the team is looking in better shape and that gives me a bit more confidence."