Bognor admit they will struggle to retain the borrowed players who helped them topple the leaders.
Striker Richard Davies (Sidlesham) and midfielder Paul Thomas (Chichester) were both borrowed from neighbouring County League clubs for the win over Carshalton in midweek which put Rocks top of the league.
Boss Jack Pearce hopes Davies will be available for the division one south trip to Met Police but is less optimistic about Thomas.
Chichester are chasing second place in the league and Thomas is also facing a 26-mile run in the London Marathon on Sunday.
Met Police's Imber Court ground is one of the less inspiring venues in the league but Pearce insists there is no excuse for slacking.
He said: "We have five games to go. I know we will show passion and commitment against Lewes and Worthing but it is the other three games I wonder about."
Gavin Geddes is back from injury for Horsham but boss John Maggs has concerns over another striker.
Steffan Ball has suffered a broken nose and may miss tomorrow's clash with Banstead.
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