|LV= County Championship Group Three, The County Ground, Northampton (day two):|
|Sussex 106 & 154-4: Van Zyl 71*; Berg 2-40, Sanderson 2-49|
|Northamptonshire 441-9 dec: Zaib 135, Rossington 87; Robinson 5-58|
|Sussex (4 pts) trail Northamptonshire (8 pts) by 181 runs|
Gareth Berg and Ben Sanderson tore through Sussex's top order once again to put Northants on course for victory.
The pace duo, who took five wickets apiece on day one, reduced Sussex to 68-4 in their second innings.
But Stiaan van Zyl made an unbeaten 71 as Sussex reached 154-4 at stumps, still trailing by 181.
Earlier, Saif Zaib's (135) maiden first-class hundred, supported by Adam Rossington's 87, helped Northants to 441-9 declared in their first innings.
Resuming on 66 overnight, Zaib quickly advanced to three figures as he and captain Rossington extended their sixth-wicket partnership to 198.
The pair were eventually separated on the stroke of lunch when Zaib was lbw attempting to sweep Delray Rawlins and Rossington followed soon after the restart, miscuing Joe Sarro (2-71) to midwicket.
With Wayne Parnell caught behind to complete Ollie Robinson's five-for, it looked as though Sussex might clean up the tail quickly, but they came up against some powerful hitting from Tom Taylor.
He struck an unbeaten 44 from 57 deliveries, while Berg contributed 38 to stretch the Northamptonshire lead above 300 before Rossington waved his men in.
Tom Haines (18) began the visitors' second innings in aggressive fashion with three early boundaries, but he was soon on his way, caught in the slips off Berg - and Aaron Thomason, Travis Head and Tom Clark soon followed.
However, van Zyl found a staunch ally in Ben Brown (30 not out) and the pair added an unbroken 86 partnership to give Sussex a bit of hope of avoiding a third straight defeat.