Worcestershire Academy product, Reeve Evitts, denied Warwickshire newcomer Alex Davies a century on the opening day of the three-day game at Portland Road, Edgbaston.
Davies, signed by the Bears from Lancashire for the 2022 season, moved onto 96 after Warwickshire had batted first following an uncontested toss.
But then Evitts, part of the 2021-2022 Academy intake, struck when Davies offered no shot to a delivery that came back in and was bowled.
He was fifth out at 174 as Worcestershire’s attack hit back following a century stand between Davies and Dan Mousley.
Five of their bowlers picked up one wicket apiece before the declaration at 287-5 from 74 overs.
Worcestershire openers Tom Fell and captain Jack Haynes made a positive start in putting on an unbroken 75 by the close.
Spinner Josh Baker broke the Warwickshire opening partnership on 109 when Henry Cullen stumped Mousley (44).
The last ball before lunch brought a wicket for seamer Cameron Jones as Tom Fell caught Matthew Lamb at first slip.
Fresh from his four-wicket haul against Hampshire, Dillon Pennington bowled an impressive post-lunch spell in which Adam Hose (2) was caught behind.
Mitchell Stanley disposed of Jacob Bethell (14), who could only find the hands of Jacques Banton at gulley.
After Evitts dismissed Davies, an unbroken stand of 113 between Ethan Brookes (50) and Olly Stone (65) lifted Warwickshire to the declaration.
Pennington had figures of 12-3-27-1, Stanley 6-0-32-1, Evitts 10-2-45-1, Ben Parker 8-2-35-0, Jones 10-2-34-1, Baker 18-4-60-1, Olly Davidson 6-0-20-1 and Banton 4-0-33-0.
Haynes and Fell scored freely when Worcestershire began their reply with 20 overs remaining.
There were eight boundaries in Haynes’s unbeaten 39 and seven fours in Fell’s 36.