Calum Davenport is gearing up to face his former club as Tottenham Hotspur visit Upton Park on Sunday - and he knows the Hammers must deliver a better performance than last week.
"It was unacceptable," he said. "All the players and staff are aware of that. In a big game like that to go over to Charlton and get done 4-0 is a really bad result. We've looked at it and maybe the first goal is offside, but once that's gone in we basically crumbled and that's not good enough."
"We've got to pick ourselves up, which I think we have done and we've looked sharp in training. But it's at the weekend when it counts. We need to respond, especially for the fans because we gave them nothing at the weekend - the game was over by half-time."
"We were aware it was a big game, we didn't perform and it cost us dearly in the end. But we have to look at the positives: we've still got ten games to go. We've been saying it for the last few weeks that it has to start this weekend, but we've got a London derby against Tottenham and it really has to. It's crunch time now."
The 24-year-old defender believes Hammers fans have been phenomenal - and they still have a massive part to play this season.
"I'm a fan myself and when we came out for the second half at the Valley I looked up and I couldn't believe everyone was still there," he said.
"Tottenham's away form this season hasn't been the best, I think they've only won a few games away from home all season so coming to Upton Park, with the fans that we've got, will be difficult for them.
"We need the fans behind us from the start and I'm sure
they're aware of that. Then hopefully we can show them that
we're going to turn up this weekend."