Scott Langridge struck twice to keep Burgess Hill firmly in line for the title.
His double set up a 3-0 home win over neighbours Hassocks in front of almost 300 fans at Leylands Park.
Delighted boss Gary Croydon said: "We are really playing well at the moment and grafting hard when we have to."
Langridge's opener was followed by Hassocks' best spell just before the break.
But he struck again with a bullet header from Richard Carter's free kick and Des Guile's near post strike rounded things off.
Sidley kept up the heat as Chris Copley and Peter Baker clinched a precious 2-0 verdict over Wick.
In-form Selsey ended Pagham's hopes with a thrilling 3-2 win at Nyetimber Lane.
Darren Lowery struck twice before veteran Barry Rishman nodded the winner. Steve Poulton got both for the Lions.
Struggling Whitehawk threw themselves a lifeline when Matt Goodchild put them one-up at Saltdean.
Tigers levelled late on when John King sent Ian Costello clear and boss Sean Bean said: "That point should see us safe."
Eastbourne United added to the worries of neighbours Town with a 3-1 win at the Oval.
United boss Micky French admitted: "I don't want Town to go down but we had to look after ourselves today."
Hard working Dave Harris rounded things off after an own goal and Tobi Hutchinson had put United on course.
Meanwhile, John Crumplin is stepping down as joint-manager of Three Bridges.
The former Albion defender will quit the club at the end of the season, leaving co-boss Darren Barker in sole charge next year.
Crumplin has previously stated his desire to manage at a higher level and he is hoping this move will help him achieve that goal.
He said: "I am going for a career as a personal trainer. Hopefully with my coaching badge that will help me get in at a higher level.
"I won't be playing in the County League next year but I am open to negotiation to play for any club at a higher level."
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