St James continue to lead Division Two and look set for promotion.
Steyning are in second place, 16 points behind with a game in hand. Sidley, Stirlands and Littlehampton form the chasing pack.
A five-wicket win against Lewes gave St James their sixth win of the season, with South African left-arm spinner Mark Johnson, the league's leading wicket-taker, playing a major part.
Johnson took 7-58 in 22 overs as Lewes struggled to 160-9 declared, Richard Eborn making top score of 47 not out.
Ed Hart with 41 was the best of the home batting as they reached 161-5, all five wickets falling to the Pakistani paceman, Kashif Ibrahim, who took 5-70 in 16 overs.
Steyning enjoyed a seven-wicket win at home to bottom club Cuckfield after dismissing their opponents for 185.
In that total, Jonathan Goodwin made 49 and Neil Fairall 64.
The in-form Steve Collins led the victory bid with 73, and Andy Ridley struck 53 not out as Steyning reached 187-3 to gain their sixth league win of the season. They are also in the cup semi-finals next weekend.
Roffey continued their improvement with a four-wicket win at Stirlands, who they restricted to 210-6 declared, of which Danny Cox made 53 not out.
In their winning score of 211-6 from 48.2 overs, Roffey owed much to 43 from Darren Dance and 41 from Simon Shivnarain.
Sidley remain outsiders for a promotion bid after winning by four wickets at Littlehampton.
The home side struggled to 164-9 declared with 44 from Richard Vokes and 38 from Danny Rive.
Tyrone Wildman returned to the Sidley side to take 4-60, and Paul McDonald grabbed 3-53.
But it was Pakistani all-rounder Intikahb Alam who, almost single handedly, won the game.
He hit 112 not out in Sidley's winning total of 169-6.
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