Relegated Worcestershire remain a factor in the fate of this year's County Championship title, but only just after they lost 13 wickets in the day at Hove.
Mushtaq Ahmed was yet again the driving force as Sussex put themselves on the brink of retaining their title by forcing Worcestershire to follow on.
He took his match haul to nine wickets for 157, going past 450 victims for Sussex in the process, while in the process claiming two lbw decisions against Graeme Hick in the same day.
Hick lasted only as far as the fifth full over of the morning before being trapped in front trying to pull for 16. And, when he then got done again, this time for 22 after picking the wrong ball to sweep, he had missed out on his last chance to claim 1,000 first-class runs in a season for Worcestershire for the 20th time.
Instead, it was two of Steve Rhodes' new young blades, Daryl Mitchell and Moeen Ali, who did most to hold up the holders.
Mitchell carried his bat for a dogged 70 as Worcestershire were bowled out for 213 midway through the afternoon. And then Moeen took command in the second innings, ending the day unbeaten on 76, just two short overnight of beating his career best for the second game running.
But, although Moeen had last night received sterling support from his skipper Gareth Batty (32) in an unbroken sixth wicket stand of 73, the weather forecast is set fair. And it will surely be only a matter of time before Sussex start celebrating today.
In that event, only an improbable run chase by Lancashire, who have been set 489 to win at The Oval thanks to a once again Mark Ramprakash-inspired Surrey, will stop them bagging the silverware again.
For the moment, Durham have gone top following their eight-wicket win at Canterbury. But, after Mushtaq had followed a first-innings sequence of three wickets for four runs in seven balls with a near-identical surge of three for four in 11 second time round, Worcestershire's fate was surely sealed - and the Riversiders' too.
Worcestershire were doubtless banking on veteran Hick to help them bat out the last two days. But the 41-year-old wonder went to pull Mushtaq on length an picked a variation ball, which hurried on to have him lbw well back in the crease.
Mitchell and wicketkeeper Steven Davies then came through the first hour of their examination by Mushtaq from the sea end - and the seam of Lewry and Chris Liddle from the opposite direction. But Davies betrayed his hard work when he drove off-spinner Ollie Rayner to cover, and Josh Knappett's lunge forward at Mushtaq soon resulted in a bat-pad departure into the hands of short-leg.
Skipper Batty hinted at worthwhile assistance, not for the last time in the day, either side of lunch only to become yet another bat-pad victim for Mushtaq. But that kick-started his team's terminal collapse.
After Kabir Ali had gone back to be lbw to the wrist-spinner, Worcestershire's last three batsmen could not muster a run between them. Mushtaq and Lewry's old-ball swing cleaned up to leave Mitchell stranded after keeping out 259 balls and batting through 88 overs.
He returned for a reprise ten minutes later. And, by the second over, he was deserted once again by opening partner Stephen Moore who aimed a cut at Robin Martin-Jenkins and lost his off stump when the ball jagged back.
Moeen emerged as a sturdier ally, and Worcestershire looked all set to come through unscathed up to tea until Mitchell finally suffered a lapse of concentration and was bowled shouldering arms at Rayner.
Hick counter-attacked Mushtaq in a short spell from the Cromwell Road end, but when the Pakistani switched back to Plan A he soon had the former England batsman lbw sweeping.
Davies then popped a catch to short-leg for a fourth-ball duck, and Knappett's chosen technique of stretching forward to Mushtaq back-fired for the second time when he missed on the defence and lifted his back leg.
Wicketkeeper Andrew Hodd fluffed an opportunity for a second stumping soon afterwards, Moeen surviving on 66 when he missed with a charge at Mushtaq. And, with the young left-hander still unbeaten, the cost of that miss remained imponderable.