Sussex bounced back from defeat in their opening game of the YB40 to comfortably beat Northamptonshire by 61 runs on D/L at Wantage Road.
That proved more than enough as the Steelbacks were reduced to 122-9 when rain brought a premature end in the 27th over having been set a revised target of 195 from 33 overs following a short break earlier.
Chris Jordan claimed career best List A figures of 3-20 from 5.3 overs while Chris Liddle took 3-31 from five overs.
Sussex got off to the worst possible start after Joyce won the toss and elected to bat as they lost Luke Wells, Matt Prior and Rory Hamilton- Brown inside the first six overs.
Wells fell for just two as he edged to first slip off the bowling of David Willey while Prior followed in the next over as he was caught behind to give Copeland his first wicket.
Hamilton-Brown’s slow start to the season continued as he played on trying to slog Copeland having made three to leave the Sharks in deep trouble on 12-3.
Joyce and Nash set about rebuilding the innings to get Sussex to 31-3 after ten overs before accelerating to reach 86-3 after 20.
Nash offered a tough caught and bowled chance to Matt Spriegel when he was on 42 but otherwise the pair played superbly.
Joyce reached his half century first – off 61 balls with three fours – with Nash following in the same over by hitting Spriegel for four to pass 50 off 68 balls.
The Sharks looked in a decent position on 143-3 with ten overs to go and began to step up the tempo with Joyce pulling Copeland for the only six of the innings.
But just as they got going Joyce was dismissed in careless fashion for 90 – the third time he has been out on the 90s this season – turning a ball from Copeland straight to short fine leg.
Nash brought up to 200 by paddle-scooping Copeland for four but he fell five short of his century when he chipped a catch to mid-wicket off the same bowler.
Sussex’s innings petered out in the final six overs as they lost four wickets for 34 runs with Copeland also dismissing Ben Brown and Chris Jordan to complete an excellent spell.
Only Joyce and Nash made double figures in a Sussex total of 215-7 which looked about 30 runs short but Northants made a real meal of the run-chase as they struggled to 78-4 when the rain came after 19.1 overs.
Stephen Peters was trapped lbw by Jordan for 20 and Alex Wakely followed six balls later as he guided a short ball from James Anyon straight to Rory Hamilton-Brown at backward point for four.
With spinners Mike Yardy, Michael Rippon and Nash keeping it tight the frustration grew for the Northants batsmen with Kyle Coetzer and David Sales both falling trying to hit over the top.
Coetzer miscued a pull up in the air to Rippon at mid-on to give Anyon his second wicket while Sales slogged straight to Prior on the square leg boundary having made 24.
A short rain break made the task even harder for Northants with a revised target of 195 from 33 overs.
The Steelbacks continued to lose wickets at regular intervals as they tried to increase their scoring rate with Yardy removing Spriegel and Liddle getting rid of Ben Duckett and David Willey.
Jordan bowled Andrew Hall and Stephen Crook to leave Northants on 122-9 when the rain brought the game to a premature end.
Sussex travel to Edgbaston to play Warwickshire on Sunday.