Openers Daryl Mitchell and Brett D'Oliveira completed another century stand to lead a strong Worcestershire reply with the bat on day two of the Specsavers County Championship match with Sussex at Hove.
Sussex totalled 579-8 declared off 145.1 overs before declaring mid-way through the afternoon session.
Then Mitchell and D'Oliveira responded by adding an unbroken 139 off 44 overs.
Mitchell continued his purple patch which has brought successive scores of 120, 161, 78 not out and now this important knock of 85 not out from 141 balls with one six and 15 fours.
D'Oliveira also showed great determination in battling through to 43 not out off 123 deliveries with six boundaries.
Both players had a let-off with Mitchell dropped at slip on 14 by Chris Jordan off Jofra Archer and D'Oliveira on 23 surviving a nick to keeper Michael Burgess off Vernon Philander.
But otherwise they played with great authority to give Worcestershire an ideal platform heading into the third day in their bid to reach the initial target of 430 to avoid the possibility of being asked to follow on.
Mitchell brought up the half century partnership with successive fours off Archer and also collected three boundaries in an over from Philander.
He went to his own half century via a four to third man off Steve Magoffin out of 78-0. The 33-year-old then slashed Archer for a six via a late cut late in the day.
Sussex resumed on 339-3 from 96 overs with Luke Wells on 139 and Luke Wright 27.
Nathan Lyon made the first breakthrough of the day when Wells, having made 155 off 288 balls with 22 fours, came down the wicket and lost his leg stump.
His stand was worth 74 in 24.3 overs with Wright.
Wright brought up his half century off 93 balls and then upped the tempo before Ed Barnard brought about his downfall.
He was undone by a slower ball and D'Oliveira ran back from point to take a superb one-handed catch.
Wright's 87 came off 118 deliveries with three sixes and 10 fours. Sussex added 125 off 29 overs in the morning session with lunch taken on 464-5 from 125 overs.
Barnard enjoyed another success when Burgess (46) was bowled by a delivery which kept low at 466-6.
David Wiese hurried to a 42 ball half century and added 99 in 14.2 overs with Jordan (37).
Skipper Joe Leach accounted for Jordan who lofted a wide delivery to Joe Clarke at mid off.
On the dismissal of Wiese for 66 from 53 balls, held at long on by Ross Whiteley off Leach, new captain Chris Nash declared on 579-8.
Leach finished with 3-101 from 27.1 overs and Barnard 3-120 from 21 overs.