Sussex suffered an alarming batting collapse to leave their County Championship clash with Essex finely poised going into the final day.

Chris Nash had put Sussex in a strong position by following his first innings century with a fine 92 before Essex fought back.

Jamie Porter and Graham Napier took nine wickets between them in the evening session as Sussex slumped from 165-2 to 282-9 at the close.

That gives them a lead of 322 having earlier bowled Essex out for 320 with Steve Magoffin and Danny Briggs taking identical figures of 2-52.

Sussex had looked in complete control when Nash added 97 for the second wicket with Matt Machan from just 105.

The pair punished some wayward bowling from Matt Dixon and Ravi Bopara but the return of Porter and Napier changed the momentum of the game.

Napier strangled Machan down the leg side for 47 and then Porter removed Ross Taylor for 22 when he was well caught at second slip by Tom Westley.

Sussex were still in the box seat on 170-3 at tea but the evening session belonged to Sussex as Porter picked up the wickets of Luke Wells, Ben Brown and Ollie Robinson during a marathon spell of 18 overs up the hill.

Napier claimed the key wicket of Nash eight short of completing his second century of the game and also removed George Garton and Danny Briggs.

Ajmal Shahzad and Steve Magoffin halted the Essex charge by adding 40 priceless runs for the final wicket and will hope to stretch the lead further in the morning.

Essex had suffered a similar collapse in the morning after Ryan ten Doeschate and Graham Napier had stretched their partnership to 89.

Skipper ten Doeschate was superbly caught by Briggs at first slip off the bowling of Robinson for 51 and Napier followed soon after when he was trapped lbw by Shahzad for 45.

Briggs wrapped up the innings when he hit Dixon in front for just one as Essex went from 308-7 to 320 all out.