Eastbourne suffered their sixth defeat of the season as they went down by seven wickets to East Grinstead on Saturday.
The defeat puts Eastbourne in severe relegation trouble as they are 36 points adrift at the bottom of the table.
Eastbourne won the toss and decided to bat and were off to reasonable start. Skipper Mark Tomsett made 17 from 28 balls before he was caught by Matt Heppell from the bowling of Lewis Hatchett.
Fellow opener Dan Wells was also going along nicely when he fell for 23 from 49 deliveries.
Sussex professional Callum Jackson went cheaply for just six runs and Aussie overseas player was snared by Craig Fowle for nine.
Matthew Green was trapped LBW for 19 runs before Tom Johnson (33) and Jamie Goddard (44*) offered some stubborn resistance.
Ed Giddins stuck around for 45 balls before he was dismissed for 19 as Eastbourne set a total of 185-8 from 58 overs.
East Grinstead rarely looked troubled in response.
Giddins gave Eastbourne a glimour of hope as he trapped opener Dan Hopkins for nine but William Adkin (22), James Adkin (31), Toby Margetts (61) and Danny Irvine (57) had more than enough runs in them to guide them to a crucial victory.
Meanwhile the Sussex Premier League leaders Preston Nomads were frustrated by a waterlogged ground at Roffey.
Their game was called off on Saturday but a surprise defeat for last season’s champions Hastings, at Bexhill, meant they were leapfrogged into second place by Horsham who won a tight game by three wickets in the last scheduled over against Worthing.
Bexhill put Hastings in at The Polegrove and disciplined bowling was matched by some impatient batting and it was only a chanceless 98 not out from skipper George Campbell that took Hastings to 202 all out in 58 overs.
For the home side teenage off spinner Jamie Bristow-Diamond continued his recent run of form with 4 for 45 and there were two wickets each for Malcolm Johnson and Callum Guest.
It was Malcolm Johnson who led his side from the front with the bat as he made 88 and with Aussie wicketkeeper Andrew Harriott hitting 68 not out, Bexhill won by seven wickets with six overs to spare.
16 year-old Elliot Hooper took 2 for 53 as the pick of the visiting bowlers.
Worthing batted first at Horsham and were dismissed for 184 with 62 from skipper Darryl Rebbetts and 53 from Benn Challen.
For Horsham Michael Munday took 4 for 43 with his leg spin and Rob Wolley grabbed 3 for 35.
Youngsters Will Beer and Devon Endersby were the men in form with the bat for Horsham who eased to a three wicket victory at 188 for 7 in the final scheduled over.
Beer hit 53 and Endersby 50 for the winners who are now just five points behind Preston Nomads at the top of the table.
Chichester were put in at Brighton and Hove and sent tumbling to just 87 all out as Matt Wood took 4 for 25 and Michael Rippon 3 for 18.
Rippon then hit 41 not out to steer the home side to victory at 88 for 3 in 27 overs.
ABOVE: skipper Mark Tomsett faces a huge relegation battle