Sussex 143 (White 4-23, Procter 3-37) and 83 for 2 lead Northamptonshire 97 (Robinson 4-42, McAndrew 3-25) by 129 runs
Sussex seamer Ollie Robinson, overlooked for England's Test squad, bounced back to equal his season's best tally of four wickets for 42 as Northamptonshire were skittled for 97 on an eventful opening day of this Vitality County Championship match at Wantage Road.
Robinson, who claimed identical stats against Yorkshire at Hove, took some stick in his opening overs, but found more control and a better line as he switched ends amid a Steelbacks collapse. This after the hosts had raced to 43 without loss inside six overs before Nathan McAndrew started the slump with two wickets in two balls.
On a day which saw 22 wickets fall, Sussex had themselves been bowled out earlier for 143, Northamptonshire seamer Jack White striking with four wickets for 23 runs, his first scalps of the summer since returning from injury. The visitors were undone by some testing seam bowling on a green top with bare ends, the bowlers finding plenty of movement to beat the bat consistently with Sussex losing six wickets for 47 in 19 overs after lunch, despite a series of dropped catches from the hosts.
The clatter of wickets meant Sussex were batting again at 5.20pm when, with the sun putting in a late appearance, conditions started to ease. Tom Haines took advantage, hitting 45 as Sussex closed on 83 for 2, 129 ahead.
Earlier Haines was first to go in Sussex's first innings, flashing outside off stump, caught at fourth slip by Matthew Breetzke to give White his first wicket.
Daniel Hughes top scored with 35, stroking five boundaries before he was dropped by a diving Prithvi Shaw at second slip off Luke Procter. His reprieve was shortlived as he edged the next delivery behind. Procter soon picked up another when James Coles fell to a good low catch by Breetzke at midwicket.
Tom Alsop then departed on the stroke of lunch when tried to work Justin Broad off his hip and was caught behind.
After the interval, in-form Sussex captain John Simpson took Sussex into three figures, before the innings swiftly fell apart.
Oli Carter was first to go. He had hit consecutive boundaries through the covers before lunch but was undone when White used his height to gain some extra bounce drawing him into pushing outside off stump, keeper Lewis McManus taking the catch.
Simpson almost fell soon after, but Shaw shelled a simple chance at second slip off White. The bowler persevered, striking later in the same over when he jagged one back in to trap Fynn Hudson-Prentice lbw.
Simpson offered a second chance in the slips off Ben Sanderson, but this time a diving Breetzke could not hold on. He finally fell when Broad gratefully pouched a catch at second slip to give White his fourth wicket. Next Procter had McAndrew caught behind by a diving McManus before Robinson fell first ball, top-edging a return catch to Sanderson.
Jack Carson meanwhile took the aggressive route as wickets tumbled around him. He clubbed the ball through the on side and scooped for six before holing out off Sanderson.
When Northamptonshire batted, Ricardo Vasconcelos pummelled 16 off the opening over from a wayward Robinson, including a six and two fours before pulling Sean Hunt out of the ground for another maximum. He had moved to 33 when he tried to steer Hunt past fourth slip, Carson taking a superb diving catch.
McAndrew then picked up two wickets in two balls thanks to some stunning fielding at third slip from Haines, who first took a good low grab to dismiss Emilio Gay, before an even more spectacular diving catch away to his left as Procter went first ball. South African T20 international Breetzke, playing his first Championship match, was then adjudged lbw to give McAndrew, Northamptonshire's fourth wicket to fall for 16 runs in three overs.
Shaw looked a class apart, driving his first two deliveries from Hunt square for four. He took a liking to McAndrew too, smashing him through the covers and cracking him away off the back foot.
But Robinson found a better line and control from the David Capel End and struck on the stroke of tea, Rob Keogh falling to a juggling catch by Coles at slip. He struck again soon after the interval when McManus drove loosely outside off stump and was well caught by a leaping Simpson.
Hudson-Prentice made the key breakthrough, removing Shaw, caught by Carson off the leading edge for 31, before Robinson claimed a third wicket, shaping one back in to bowl Sanderson. In his next over he had Raphael Weatherall brilliantly caught by Carson at short cover before taking a catch in the deep himself as Broad holed out off Hudson-Prentice.
When Sussex batted again, Northamptonshire made an early breakthrough when White trapped Hughes lbw for 13. Haines though decided attack was the best option, smashing eight boundaries as he and Alsop shared a stand of 63 before he was caught behind off Sanderson.