Neil McRoberts accepts Portsmouth need to get their London Three South West promotion bid back on track against table-topping Reeds Weybridge at Rugby Camp (2.30pm).
Two successive league defeats have dented the city club's title ambitions ahead of what could be a pivotal weekend.
'There is no escaping that this is a huge game for us against one of our closest rivals,' said the senior coach.
'A win will put us right back on track.
'There is still a lot of rugby to be played but after two defeats we need to go out and do the job.
'Another reverse would make things very hard for us.
'We are very much focused on producing a performance that will enable us to come out on the right side.
'Weybridge are a good side and we know that if we don't play a structured game they can hurt us.
'We will set out to be physical up front and attempt to establish some dominance.
'Our three-quarters will need to make sure they remain tight in midfield.
'If we can nullify their backs then I think we will win.
'If we play the structured game that we are capable of, we will give ourselves every chance.'
The home side give a debut at scrum half to Ben Smith who has signed from United Services Portsmouth.
Youngster Tim Rollett has performed admirably in this position but for such an important game - Reeds are 100 per cent after six games - the hosts are opting for Smith's extra experience.
Smith also possesses a good kicking game which could prove vital in a close contest.
A host of first-choice players return in the three-quarters, with Robert Lamberton, Luke Simmons, Noah Cannon, Matt Farnes and Mark Ovens all back after missing last week’s Hampshire Bowl win at Fareham Heathens.
Sam Foster is back to partner Daz Leggat in the second row, while Matt Hoban, Tim Snowden and Rhys Bowen form a formidable back row.
McRoberts is clear where his team need to improve.
'In our defeat at Weybridge Vandals we didn’t start playing until after half-time,' said McRoberts. ‘We can't afford to do that again.
'The players need to show their character from the start.
'We have to ensure that we don't play into our opponents’ hands.
'In the last couple of weeks a few questions have been asked of us.
'Despite this, we are not pressing the panic button and have the quality in the squad to recover it.
'We just need to go out and do the job.'