Worcestershire fought back strongly with the ball during the afternoon session of a tough third day in the LV=Insurance County Championship match with Sussex at the 1st Central County Ground at Hove.
They secured a first innings lead of 62, with Jake Libby dismissed for a superb 198 in the first over of the day.
Worcestershire’s total of 410 secured four batting bonus points to add to their three for bowling.
Sussex then reached 143-0 in their second innings before Matthew Waite and Adam Finch altered the picture by both striking twice during a period where five wickets fell for 35 runs between lunch and tea.
But the balance of the game altered again during the final session, and half centuries from Fynn Hudson-Prentice, Tom Alsop, and Jack Carson steered Sussex to 359-6 from 93 overs by the close – a lead of 297.
Libby was dismissed from the fourth ball of the day when he was caught at second slip off Ari Karvelas.
He struck 28 fours in his 261 ball knock, and his century was the fastest of his career, coming from 141 deliveries.
Worcestershire had a first innings lead of 62, and there was an intriguing contest between Joe Leach, the hero of the first innings with six wickets, and Sussex opener Tom Haines.
Haines played some fine strokes, predominantly through point and cover, but he also played and missed on several occasions.
He survived the new ball and with Tom Clark scored freely in bringing up the 100 partnership from 22 overs.
Waite bowled a challenging post-lunch spell and beat Haines all ends up with a superb delivery which swung and went past the inside edge.
It was Leach who made the first breakthrough of a spell in which four wickets for four runs in the space of 21 balls.
Haines (91 from 96 balls) was undone by a ball which swung away, and Jack Haynes held onto the chance at slip.
It was Leach’s 32nd wicket of the season.
The next delivery – bowled by Waite – also brought a reward for Worcestershire as Clark (50) nicked another swinging delivery and was taken by keeper Gareth Roderick.
Finch came into the attack and struck in successive overs.
James Coles (2) attempted a pull shot but only skied the ball on the on side, and captain Brett D’Oliveira made ground from mid-on to mid-wicket to take an excellent low catch.
It became 147-4 when Sussex keeper-batter Oli Carter looked to work Finch on the leg side and was lbw pinned in the crease.
The ball was reverse swinging, and Dan Ibrahim was dropped at first slip off Waite on 19, but it was not a costly miss.
He had added only nine more runs when he pushed forward to Waite and was lbw at 178-5.
Sussex’s lead at that stage was 116, but they recovered thanks to Fynn Hudson-Prentice’s half century and a partnership of 82 with captain Alsop.
Usama Mir entered the attack and struck with the first ball of his spell.
Hudson-Prentice (54) made room to cut the Pakistan leg spinner but feathered the ball through to Roderick, who made no mistake.
Carson, on four, survived a sharp chance to slip off Mir with the total on 270-6 before Alsop completed a solid 130 ball fifty.
The second new ball was immediately taken after 80 overs with the total on 310-6.
Carson was fortunate on 27 to spoon a delivery from Leach back over his head but short of D’Oliveira at mid-on.
He remained undefeated on 52 with Carson 67 not out at the close.
Leach ended with figures of 20-4-78-1, Ben Gibbon 16-4-54-0, Usama Mir 22-2-81-1, Finch 19-2-71-2, Waite 15-3-64-2 and D’Oliveira 1-0-5-0.