AFC Portchester and United Services clash in an FA Vase derby at Burnaby Road tomorrow (3pm).
Wessex League premier division Royals will start as firm favourites against their division one hosts.
But Bob Brady’s Services will be intent on causing an upset.
Portchester boss Graham Rix knows his team must be fully committed to the task.
He said: ‘It is a big game and great opportunity for both teams.
‘We certainly won’t be able to take anything for granted and can’t afford to underestimate the opposition.
‘If you don’t approach a game like this in the right manner you can easily come a cropper.
‘There will be shocks in this round and we have to make sure we are not one of them.’
Rix is hoping he can call on Danny Audin, Gary Moody and Sammy Igoe this weekend.
Audin and Moody have been out injured for two months but Igoe managed to get 30 minutes under his belt at Hamworthy United.
Services manager Brady knows his team will have to show a big improvement if they are to cause an upset.
They suffered a disappointing 4-0 defeat at Pewsey Vale in their last outing.
‘We will need to work a lot harder, be far more competitive and give it our best shot,’ said Brady.
‘It is the first time we have reached this stage of the competition and want to make the most of it.’
Horndean include former Pompey forward Ashley Harris in their squad for their Vase tie against Ascot United at Five Heads Park (3pm).
Deans boss Dave Carter has checked out the opposition.
He said: ‘I have watched Ascot and believe we have a chance.’
In the Wessex League premier division, Moneyfields face Hamworthy United at Dover Road (3pm).
Jack Lee is likely to replace suspended captain Tom Chapman.
Petersfield Town face a difficult test at in-form Brockenhurst.
Fareham Town will be looking to get a valuable three points as they travel to Totton & Eling.