Worcestershire's veteran seamer Alan Richardson claimed a career-best 8-37 against Gloucestershire on the opening day at New Road.
Gloucestershire were all out for 234 in 70.3 overs and, at the close, the Worcestershire had reached 65-0 in reply with skipper Daryl Mitchell unbeaten on 46.
Richardson, 38, quickly carried on where he left off in Worcestershire's previous game when he bagged match figures of 12-63 in a two-day, 10-wicket demolition of Kent at Canterbury last week.
He ensured it was an unproductive return to New Road for Gloucestershire skipper Michael Klinger, who played in six Championship games for Worcestershire when he deputised as the club's overseas player before Phil Hughes' arrival last season.
The Australian scored just five before he pushed forward and was trapped leg before by Richardson, who soon went on to capture Dan Housego during an opening spell which yielded figures of 7-0-12-2.
Chris Dent went on to complete a half-century partnership with Alex Gidman before he pushed forward on the back foot off Richardson and was caught behind by Michael Johnson. Dent departed soon after lunch when undone by a Richardson delivery which cut in and knocked back his off stump for 41, which contained eight fours.
At 99-4, Gloucestershire needed stability which was provided by Hamish Marshall and Benny Howell who steadily constructed a half-century stand in 14 overs. Their partnership spanned 20 overs and produced 74 runs before Mitchell's first ball accounted for Howell for 36.
Mitchell then highlighted his fielding abilities in the next over by holding on to a low, one handed reflex catch at second slip to remove Marshall for 45 off paceman Chris Russell.
Jack Taylor, accompanied by Gareth Roderick, pushed Gloucestershire past the 200 mark in the 61st over by striking Russell for fours in a row and at tea Gloucestershire were 219 for six off 64 overs.
Richardson struck with the third ball after break by ousting Taylor to complete his third successive five-wicket return and then went on to dismiss James Fuller, Craig Miles and Roderick to complete a spell of four wickets for eight runs in 3.3 overs.