Peterborough United boss Darren Ferguson admits a fifth straight defeat in the league at Brentford this evening is not an option.

Posh's slump in the league continued at home to Stevenage on Saturday and Ferguson believes that anything other than victory at Griffin Park could spell the end of their hopes of automatic promotion, even at this early stage.

Peterborough are eight points off second-placed Wolves, who come to London Road on Saturday, and Ferguson doesn't want to concede any more ground to them and leaders Leyton Orient.

'We need to get a win soon and we need to work quickly,' he said.

'To get a promotion you've got to go through a lot of pain and anguish. You can't underestimate how much it takes to do that. The most important thing is Tuesday - we simply have to get a result in that game.'

Ferguson is sweating on the fitness of Britt Assombalonga, who missed the weekend defeat with a thigh problem.

'Britt's got a problem with his thigh and he's 50/50,' Ferguson told the official club website.

'We couldn't risk him (against Stevenage) in that he has got a large bleed in there and if it does go properly you are talking six to eight weeks. There was no way I was going to do that.'

If Assombalonga doesn't make it Kyle Vassell could remain in the side despite enduring a difficult debut against Stevenage.

'I felt sorry for Kyle, I really did. To be involved in that first half performance, I felt for the boy.

'It was a difficult result to take for everyone – I know the boys have got to improve but the players in the dressing room need to start taking more responsibility.'