Ed Barnard registered the first five wicket haul of his career as Somerset were bowled out for 202 on the opening day of the Specsavers County Championship match at the Cooper Associates County Ground, Taunton on which 18 wickets fell.
The Worcestershire all-rounder produced a deadly four wicket blast after lunch to finish with 5-52 from 16 overs.
Australian left hander Matt Renshaw hit a splendid unbeaten 101 on his debut for Somerset.
But only James Hildreth (48) of the other batsmen lasted long against the four-pronged Worcestershire pace attack.
It was the second successive match in which they had collected maximum bowling points and, unlike at Hampshire, there was no late order resistance to hold them up.
But then Worcestershire also lost wickets at regular intervals with Travis Head providing the most resistance in making 49 and Barnard 27 not out as they closed on 153-8 from 39 overs.
Steve Magoffin delivered a fine opening spell for Worcestershire who bowled first after an uncontested toss and was rewarded with the wicket of Marcus Trescothick who was lbw for one.
It became 7-2 when Ed Byrom (4) was caught behind off skipper Joe Leach after he pushed forward to a delivery which nipped away a little.
Hildreth survived a chance off a skied chance to keeper Ben Cox and he and Renshaw scored freely in adding 92 in 20 overs for the third wicket.
But Barnard made his first breakthrough just before lunch when Hildreth fell to a fine low catch by Joe Clarke at third slip and from then on the Worcestershire attack took control.
Barnard had Somerset skipper Tom Abell (10) lbw and ex Worcestershire keeper Steve Davies (9) perished to Leach with Daryl Mitchell holding a head high catch at second slip.
Barnard then picked up three wickets in three overs.
Lewis Gregory (2) was bowled via an inside edge and Craig Overton (0) prodded through to Cox to give Barnard his 100th first class victim.
Barnard completed his five-for by having Josh Davey (4) lbw and he was mobbed by his team-mates who recognised the significance of the dismissal.
Renshaw off drove fellow Australian Travis Head to the boundary to reach three figures off 137 balls with one six and 13 fours.
But Josh Tongue quickly wrapped up the innings as Jack Leach (4) gloved a legside delivery through to Cox and Tim Groenewald (2) was also caught behind.
Barnard finished with 16-3-52-5, Leach 15-3-61-2, Tongue 14.1-0-42-2 and Magoffin 10-4-26-1.
Worcestershire lost quick wickets when they launched their reply with Gregory taking the first three wickets.
Mitchell (5) nicked to first slip, Brett D’Oliveira (3) was bowled and Joe Clarke (0) went for a first ball duck lbw at 17-3.
Tom Fell made 21 before he was lbw to Davey and George Rhodes (1) departed to a sharp catch at short leg off Overton.
Worcestershire were then 48-5 but Travis Head and Cox started to launch a recovery and added 45 for the sixth wicket in 11 overs.
Cox, fresh from his half century at the Ageas Bowl, moved onto 21 before he was pouched by Trescothick at second slip off Groenewald.
Head looked set to register his first half century for the County after making 45 not out at the Ageas Bowl.
But when one short he aimed a pull at Davey and dragged the ball onto his stumps at 112-7.
Leach (8) looked to work Davey across the line and was caught off a leading edge at mid off but Barnard and Tongue added an unbroken 29 by the close to reduce the deficit to 49.
