Worcestershire 267 (Cox 93, Barnard 60, van der Gugten 4-66) and 34 for 1 trail Glamorgan 381 (Rudolph 111, Cooke 93, Salter 80*, Tongue 6-97, Leach 4-85) by 80 runs
Jacques Rudolph scored his first County Championship century for more than two years as Glamorgan turned the Specsavers County Championship clash with Worcestershire on its head at New Road.
Rudolph and Chris Cooke created a new seventh wicket record of 168 in 50 overs for Glamorgan in matches against Worcestershire.
Then Andrew Salter and Lukas Carey piled on the misery for the promotion-chasing home side with a 124 partnership for the ninth wicket in 27.1 overs.
Their efforts enabled Glamorgan to recover from 58-6 at one stage yesterday evening and total 381 all out in 101.5 overs - a lead of 114.
It was in sharp contrast to the problems caused yesterday by Worcestershire paceman Josh Tongue with his five wickets in four overs although he still was able to return career best figures of 6-97 from 25 overs.
Worcestershire suffered an early setback in reply when Daryl Mitchell on 18 nicked skipper Michael Hogan to Colin Ingram at first slip as they closed on 34-1 after bad lighted halted play with seven overs remaining.
Rudolph reached three figures in the competition for the first time since his hundred against Leicestershire at Grace Road in April 2015.
It was a welcome tonic for the 36-year-old after a poor run of form and having recently relinquished the captaincy of the Championship side to Hogan.
Rudolph and Cooke batted in confident fashion in surpassing the previous seventh wicket record of 106 by Jonathan Hughes and current head coach Robert Croft at the same venue in 2002.
Tongue was the only bowler to cause them any worries in his initial two spells and Rudolph completed his 51st first class hundred - off 158 balls with 13 fours - with a cut for four off Nathan Lyon.
Cooke had a let off on 48 when Daryl Mitchell at first slip failed to hold onto a chance off Lyon.
The stand was finally broken with Leach dismissing the pair in the same over.
Cook, having made 93 off 113 balls with one six and 11 fours, was caught at short mid on and then Rudolph, whose 111 spanned 209 deliveries with 14 boundaries, was bowled after attempting a cut.
Glamorgan were still 40 in arrears at that juncture but Salter and Carey earned them a sizeable advantage as they both posted career best scores. Salter deliberately upper cut Tongue over third man for six to bring up the fourth batting point as the runs flowed against the second new ball.
Tongue finally ended the stand when Carey (54) popped a simple catch up to Brett D'Oliveira at point and then Leach removed Hogan (13) to leave Salter unbeaten on 80.