Horsham and Eastbourne share second place after Eastbourne enjoyed a comfortable eight-wicket win at home to last year's champions Brighton & Hove, while Horsham were held to an exciting draw at Cuckfield.
Skipper Jason Finch, leading his Hastings side from the front this season, top scored with 82 in a total of 271-4 as good support came from James Beeny (54) and Brad Smith (50).
Chichester lost their last wicket with just 11 balls left as they were bowled out for 193, of which David Leaver made 52 and skipper Jez Goode 40. Doing the same for the hosts were left-arm spinner Mick Glazier (6-64) and Tim Van Noort (4-30).
Sussex youngster Ollie Rayner was again the hero for Eastbourne at home to Brighton. He took 6-27 as Brighton tumbled to 85 all out, only youngsters Matt Machan (22) and Matt Green (21) offering much resistance.
Rayner then hit 49 not out off only 46 balls to take Eastbourne to victory at 86-2. Matt Wood took 2-8 in seven overs.
Preston Nomads crashed to 101 all out at Stirlands after being put in as Graham Bush grabbed 4-22 and Nathan Ball 3-15. Rob Wakeford was top scorer with 35.
But it was far from easy for Stirlands as skipper Sean Heather then hit 45 and Danny Cox 35 to get them home by four wickets. It took them 47 overs as Stephen Rigg took 2-10 and Rayad Emrit 2-28 in 17 lively overs.
Horsham found batting far from easy on a damp pitch at Cuckfield but 59 from Andrew Hodd and 60 from Luke Marshall together with a lusty 44 not out from Ansar Javed saw them to a useful 235-7 declared from 56 overs. Kris Sterling took 2-19 and Chris Mole a somewhat unlikely 2-50.
In reply Cuckfield started slowly and were handicapped by having Jack Waghorn and Peter Widdup injured in the field and only able to bat in an emergency. But a fine 112 not out from Chris Mole and 46 from Tasmanian Jason Shelton took them close at 227-5 as spinner Will Beer took 3-66.
There was another close game at Three Bridges where East Grinstead finished with nine wickets down and just 12 short of victory. Bridges made 201-7 with 46 from Mark Newell and 37 from Danny Alderman as Stuart Simmonds took 4-46.
A fine 104 not out from teenager Matt Kleinveldt then delayed the hosts and kept alive the visitors' hopes before time finally ran out. Alderman took 3-57 and Aussie Mike Shaw 3-39.
Bexhill have gone above previous leaders Lewes Priory, surprisingly beaten at home by improving Worthing, to head the promotion chase from Division 2 after an emphatic home win against Haywards Heath.
Skipper Jonathan Haffenden led Bexhill to 214 all out in 47.2 overs after being put in by Heath. Richard Matthews made 41 in what was a useful total as Hayden James took 4-35. Simon Bulteel then took 5-29 and Chris Topp 3-14 as the visitors were bowled out for just 115.
Worthing made 187-9 declared at the Stanley Turner Ground as John Kaye hit 66 and Andy Lutwyche 33 not out. Tom Sharp (5-29) and Simon Birch (3-24) kept the batsmen on their toes.
Lewes then crashed to a disastrous 17-8 before eventually being dismissed for 58 in 19.2 overs as Aussie Kyle Bowes took 5-35 and Chris Mansell 4-20.
Littlehampton won by six wickets in a low scoring game at home to Steyning, whom they dismissed for just 83 after putting them in. Top scorer was Jean-Paul Stewart with 36 as Luke Vinter and Adam Tester each took 3-23.
Angus Webster, with 21, top scored as Littlehampton reached their target in 25 overs. Ian Simpson took 2-29.
The two remaining games were drawn, with Roffey skipper Josh Fleming hitting 102 in his team's total of 266-5 before visiting Sidley held on at 214-8 as young left arm spinner Luke Barnard took 6-75.
St James's Montefiore also held on for a draw at Pulborough after dismissing the hosts for 169, of which Tom Crump made 60.
The Saints reply of 151-9 owed much to young wicketkeeper Adam Davies, who made 63.