Glamorgan 76 for 6 (Tongue 5-16) trail Worcestershire 267 (Cox 93, Barnard 60, van der Gugten 4-66) by 191 runs Scorecard
Ben Cox successfully filled the No. 5 spot vacated by the departed Tom Kohler-Cadmore before Josh Tongue caused mayhem with the ball for Worcestershire on day one of the Specasavers County Championship clash with Glamorgan at New Road.
Cox was promoted up the order for the second game running after Kohler-Cadmore's release - to join Yorkshire - was confirmed yester and he top scored with 93 out of 267 all out in 70.4.
Then Tongue blitzed his way through the Glamorgan batting line-up with five wickets in four devastating overs as the Welsh County closed on 76-6.
Cox went to the middle quicker than he would have wanted after Worcestershire had been reduced to 14 for 3 within the first 45 minutes on being asked to bat.
He eventually became the last of four victims of Timm van der Gugten who was well supported by new four-day skipper Michael Hogan, Lukas Carey and Andrew Salter with two wickets apiece.
But then Tongue got to work with the ball as Glamorgan nosedived from 39 for 0 to 58 for 6.
Worcestershire were looking for a positive response after an innings defeat at Sussex had ended a run of four successive victories.
But they were immediately on the back foot as Daryl Mitchell, who had scored 534 runs in the previous five Championship innings, lost his off stump to the third ball of the innings from Lukas Carey.
Tom Fell (7) was trapped lbw by Van der Gugten who also accounted for Brett D'Oliveira (7) with Aneurin Donald holding onto a sharp chance at third slip.
Cox was in aggressive mode from the start and Joe Clarke (25) partnered him in a stand of 69 in 16 overs before the latter was bowled by Michael Hogan with a delivery which was angled in.
Van der Gugten bowled a lengthy spell during the afternoon session and accounted for Ross Whiteley (6) who was pouched by Donald via another sharp catch at third slip.
Cox was joined by Barnard in another productive stand of 59 in 11.4 overs. The former Bromsgrove School pupil looked set for a deserved century but then became the fourth victim of Van der Gugten as Andrew Salter reacted sharply away to his left in the gully. He faced only 99 deliveries and struck 15 boundaries.
Skipper Joe Leach (13) was lbw to Hogan and Jack Shantry ((3) was caught down the legside off Carey but Barnard reached an excellent half century off 86 balls with six fours. The ex England Under-19 batsman finally holed out to mid-off off Andrew Salter for 60.
Tongue collected two boundaries in an over from Hogan costing 15 runs to bring up the 250 before Salter brought about his dismissal at deep extra cover.
Glamorgan openers Jacques Rudolph and Nick Selman put on 39, although not without the odd scare, but then the wickets started to tumble.
Selman (4) was bowled by a ball of full length from Leach - his 30th wicket of the season - and then Tongue worked his way into the Glamorgan order.
Will Bragg (7) was bowled, Colin Ingram (2) gloved a ball to first slip and Donald edged to second slip.
The procession of wickets continued as Clarke pulled off a stunning catch at third slip to dispose of David Lloyd (2) while in the same over Van der Gugten (0) was victim to an excellent catch by Cox. Rudolph was left unbeaten on 49 surveying the wreckage from the non striker's end.