West Ham manager Alan Curbishley warned his struggling side cannot afford to slip-up against Fulham.
The Hammers are without a win in four Premiership games and sit in the relegation zone, four points behind Wigan and safety.
Curbishley is confident new signings Luis Boa Morte and Nigel Quashie can inspire a change in fortunes at Upton Park - but that must start this weekend.
'We let the Portsmouth and Man City games get away from us. They were big games, three big points. We mustn't let this game get away from us,' said Curbishley.
'We have a difficult game. Chris Coleman has done a very under-rated job and you realise that when you are in the bottom three.'
'If we can get the result it may claw us back into the people just above us. We have lots of youngsters here with great potential. I felt I needed to put some steadier heads between them who won't be fazed by the situation.
'Perhaps when games are not going so well or going away from you, the senior players can help pull it around. And when you get into this position in the league it can also be difficult when you are leading games. You perhaps don't know how to close a game out.
'We have signed Luis hoping he will make some goals and score some goals because it is an area we need to improve on.
'With Nigel, we need some aggression in the middle of the park because there hasn't been much of that recently.'
Curbishley acknowledged the arrival of Boa Morte and Quashie could upset some of West Ham's established squad members.
Boa Morte, a £5million capture from Fulham, replaced left-wing regular Matthew Etherington for last weekend's 3-0 FA Cup win over Brighton.
And the signing of Quashie from West Brom piles the pressure on captain Nigel Reo-Coker and Hayden Mullins ahead of tomorrow's clash.
But Curbishley is ready to make the tough decisions as West Ham seek to avoid the drop.
'If Nigel Quashie plays this week it will upset someone, I can't avoid that. Luis coming in has also upset certain people,' he said. 'I am not saying I want to upset players - but I felt I needed to do something to keep everybody on their toes.
'I think I have done that. I have brought competition into the club. Now I hope people respond to it and we get some of the performances we need. That is all I am after.
'I am not really interested in individual problems. I have got to get that team winning some games. That is all I am after because the club comes first.
'We have got to fix the results - and that starts at the weekend. We are third from bottom and we have to get out of that.'