Southwick opened up a four-point lead at the top of Rich City County League division two after an emphatic 4-0 win over Oakwood.
Wayne Potbury and Daren Newman each scored twice as Wickers wrapped up victory inside 58 minutes.
However, while Southwick and Hailsham Town look assured of promotion places, four teams are locked in a battle to claim the third spot in division one next season.
New favourites to go up are East Grinstead following a run of six successive wins. Teenager Scott Woolley and Roger Gualtieri were the scorers in a 2-0 win at Worthing United on Saturday which raised the tally to 18 points from 18.
Worthing remain third but are just one point ahead of Peacehaven, who have three games in hand, and three ahead of both Broadbridge Heath and East Grinstead, the latter having five games in hand.
Grinstead boss Bob Smith said: "There is a real feeling among the players that we can go all the way and win promotion.
"All I would say is that we have nine extremely difficult games to play and if we win them all we will definitely go up, but there is still a lot of work to be done."
Peacehaven maintained their promotion push on Saturday with a 2-0 win at Crawley Down thanks to first half goals from Allan Ashdown and Simon Jones.
Broadbridge Heath, meanwhile, drew 1-1 at Hailsham - a result which did neither team a lot of good.
Jon Neal's 30th minute strike appeared to be enough to secure Hailsham victory but James Brown levelled five minutes from time to earn Heath a point.
At the bottom, Storrington drew 1-1 with Crowborough which left the Crows four point adrift of their relegation rivals.
James Lattimer fired Crows ahead in the first minute but Luke Baker levelled for Storrington ten minutes later with his third goal in two games and that is how it stayed.
Storrington joint-boss Bob Paine said: "We thought we could get all three points to open up the gap even further but at least it didn't get them any closer to us."
Doomed Lingfield slumped to a bizarre 9-4 defeat at home to Shoreham. Paul Roberts scored four for the hosts but ended up on the losing side.
Ben Boiling bagged a hat-trick for Shoreham, Andy Agutter and Mark Pulling hit a brace each, while the tally was completed by Chris Pulling and an own goal.
Second half goals from Kevin Rose and Mark Ward earned Westfield a 2-0 win at home to Oving.
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