|LV= County Championship Division One, BrightonandHoveJobs.com County Ground|
|Sussex 434 & 251-3 beat Lancashire 320 & 364 by seven wickets|
|Sussex 23 pts, Lancashire 5 pts|
Sussex secured safety with a seven-wicket win over Lancashire, whose top-flight future is now in serious doubt.
Lancashire have one game left and are 12 points behind seventh-placed Middlesex - beaten by Durham - and the London side also have a game in hand.
After resuming on 203-4, Steven Croft made 87 but Lancashire were dismissed for 364, with Chris Jordan taking 4-82.
Needing 251 from 59 overs, Ed Joyce (79) and Craig Cachopa (78no) helped lead Sussex home with 12 overs left.
After losing Luke Wells for 13 in the ninth over, caught by Steven Croft off James Anderson, the hosts appeared to be easing to their victory target and reached 94-1 at tea, needing another 157 runs to win with 40 overs remaining.
The dismissal of Chris Nash (57), who was caught behind by Jos Buttler after making his second half century of the match, briefly raised the visitors' hopes of an unlikely victory.
Lancashire were not helped by the absence of Tom Smith, who was unable to bowl because of a back problem sustained whilst batting earlier in the day.
Sussex upped the pace again and Joyce took 55 deliveries to reach his fifty, which he brought up with a six off Simon Kerrigan, and went on to smash two sixes and seven fours in his 80-ball innings.
He put on 105 with Cachopa for the third wicket at more than five an over, before being bowled by Croft round his legs.
Cachopa, who hit three sixes and nine fours in 86 balls at the crease, compiled his fifth half century of the summer and won the game with a boundary off Luke Procter.
Lancashire captain Glen Chapple told BBC Radio Manchester:
"We decided we had to take a chance on it. We thought we'd set them a target which was challenging, but it turned to be a little be easier than that.
"The pitch held together far better than most pitches do and I think if we're really honest, we didn't score enough runs in the first innings.
"I think taking the option to take the game to them was our best bet, but we didn't put them under enough pressure in the field.
"If we get the chance to save ourselves in the last game, then we'll be massively up for it, but obviously its out of our hands at the moment."
Sussex skipper Ed Joyce:
"My worry was we might struggle as we hadn't played for three weeks, so I'm delighted that we have banished any relegation worries. We can start looking up the table again.
"It was crucial to get the lead we did on first innings.
"It wasn't an easy chase because although it was a very good wicket as one or two balls were starting to keep very low, but we went about it really positively."
BBC Radio Sussex's Adrian Harms:
"Ultimately, this was comfortable for Sussex, who chased down the 251 to win with overs and wickets to spare.
"Ed Joyce, with 215 runs in the match, was perhaps the difference between the sides, but on an excellent four-day pitch, Lancashire just did not make enough runs in their first innings, and thereafter were always on the back foot.
"Sussex head to Trent Bridge next week and then Northampton, looking to emulate their top-three finish last season, whilst Lancashire must rely on others if they are to secure their First Division status."