Champions Brighton have moved off the bottom for the first time after a second successive win but Horsham lead the field, fielding four Sussex professionals in Chris Nash, Michael Thornely, Andrew Hodd and Will Beer as they proved too strong for visiting Chichester.
Nash hit 116, Thornely 105 and Andrew Hillman 67 not out to take their side to a massive 322-3 declared from 49 overs. The visitors were then dismissed for 219 despite 69 from Tim Bishop and 62 from David Leaver. For Horsham the leg spin of Will Beer was rewarded with a return of 5-57 and there were two wickets each for Nash and Nick Weekes.
Eastbourne, too, had a strong professional presence in their side at Cuckfield, where they won by four wickets in just 46 overs chasing a total of 257-7.
Jason Oates hit 50, Marc Gardner 43 not out and James Thorpe 38 in that Cuckfield score as Ollie Rayner took 2-58 and Raga Aga 2-32.
The excellent chase featured Mark Tomsett (61), Tom Smith (72), Ben Brown (63) and Raga Aga (42no) although Oates completed a good day personally with 5-76.
Danny Alderman cracked 102 for Three Bridges after his side had looked in early trouble against Hastings, the team who started the day in top spot. Bridges reached 248-9 as Chris Morris took 2-44 and James Beeny 3-51.
The visitors then tumbled to 130 all out despite 56 from skipper Jason Finch. For Bridges Paul Smith took 4-20 and Aussie Michael Shaw 3-28.
Preston Nomads won by seven wickets at East Grinstead after Kashif Ibrahim (3-35) and Stephen Rigg (3-16) combined to bowl out the hosts for just 119 as only Andy Shoebridge (27) offered limited resistance. In reply, Rob Wakeford (41no) and Jeremy Green (33no) completed the job.
Sean Heather's 90 in a sorry Stirlands total of 127 included 12 fours and three sixes. Brighton's Julian Stephenson (3-30) and Patrick Spencer (3-19) did much of the damage before Matt Machan (44) and skipper Spencer (33no) helped Brighton over the line with five wickets still intact. Nathan Ball took 3-48.
Lewes Priory have opened up a 15-point lead at the top of Division 2 after beating their nearest rivals Bexhill by 70 runs. Third-placed Littlehampton lost at home to Haywards Heath, while Roffey and Steyning enjoyed big wins and Worthing held on for a draw at home to St James's Montefiore.
Lewes were put in by Bexhill and reached 206-9 thanks to 46 from John Aston and 35 from James Cruickshank. Chris Topp took 3-66 before Bexhill then collapsed to 136 all out in 36.2 overs. Richard Harrison (27) and Ashley Wright (25) were leading scorers as Simon Allen claimed 3-40.
Hayden James seems to enjoy playing at the Sports Field. On Saturday the Haywards Heath all-rounder smashed 150 not out, including 11 sixes, off only 103 balls to help his side to 279-5. Charlie Dowdall helped things along with 52 as Luke Vinter took 3-57.
Littlehampton were then dismissed for 225 as Benn Challen (79) offered most resistance to Aussie paceman Joe Mennie (5-49).
Pulborough were bowled out for 162 at home by Roffey as Matt Crump top scored with 39. Sam Adams led the way with 36 in a winning reply 166-8. Lee Callaghan took 4-25.
Steyning made an impressive 227 all out at Sidley, where Dwayne Jones made 77 and skipper Andy Stillwell 74. But helping to keep it manageable were Neil Priddie (5-64) and Scott Woodruffe (3-39).
Dave Mates (4-13) and Andy Isaacs (2-34) helped bowl out Sidley for 128, of which Peter King made 32.
St James's Montefiore declared at 214-9 thanks to 50 from Stephen Ades and 40 from Fred Whitehead as Kyle Bowes took 5-76 and Andy Lutwyche 3-61. At stumps the home side were 201-8, with Alex Harris unbeaten on 38. Phil Taylor (5-39) and Kris Johnson (3-37) were the wicket-takers.