James Anyon claimed only the sixth five-wicket haul of his career and Luke Wright hit an unbeaten 74 as Sussex gained the upper hand on the first day of the LV= County Championship match against Durham at the BrightonandHoveJobs.com County Ground.
Anyon took 5-44, including four wickets for just 19 runs in his second spell, as the champions were dismissed for 164 in 52 overs after winning the toss, with their last seven wickets falling for 56.
Sussex were reduced to 90 for five at one stage before Wright led a counter-attack to take them to 186 for five at stumps as they chased their first championship win at their home ground since last August.
Durham were in a decent position at 107 for three shortly after lunch when Chris Jordan triggered a collapse by claiming wickets in successive overs.
Jordan bowled with sustained hostility to have top scorer Scott Borthwick caught at third slip fending off a bouncer after he had reached 1,000 championship runs for the season on his way to 36.
Matt Prior then dived full-length after parrying the ball at slip to remove Will Smith before Jordan's third wicket of his spell came when Ben Stokes slashed to point shortly after the ball had been changed.
Jordan had earlier claimed opener Keaton Jennings on his way to figures of 4-50, which took him to 56 championship wickets for the season.
Anyon had Mark Stoneman, who also passed 1,000 championship runs during the contest, caught behind in his second over but he was more productive after lunch when he reaped the rewards for bowling a fuller length.
At one stage he took three wickets in six balls with Phil Mustard edging an off-cutter to slip, Michael Richardson lbw playing across a straight one and Usman Arshad losing his off stump. Anyon claimed his fifth victim when skipper Paul Collingwood holed out to deep midwicket.
Durham were the last side to win a championship game at Hove when batting first, more than two years ago, and Graham Onions improved their chances of repeating that by picking up two wickets in his first two overs, trapping Nash lbw to the third ball of the innings before removing Yardy the same way.
Skipper Ed Joyce batted purposefully, dominating a third-wicket stand of 58 with Luke Wells to which his partner contributed just a single.
But when Arshad replaced Onions he induced Joyce to play on five runs short of a fifty and then picked up Prior's prime scalp when he edged behind. Wells' vigil ended when he got a thin edge to Stokes' outswinger to leave Sussex 90 for five.
But Wright and Ben Brown responded impressively, with the former recording a 38-ball half-century before being at deep extra-cover on 57 by Stoneman.