Wayne Parnell made a telling contribution with bat and ball on the second day of the Specsavers County Championship clash with leaders Surrey at Blackfinch New Road.
The South African all-rounder made a disciplined 42 which helped Worcestershire to secure a third batting point as they were bowled out for 336 in 116.4 overs.
Then Parnell made a treble breakthrough with the ball – including wickets with successive balls in his first over.
He left the field with the webbing on his right hand strapped up after fielding a return drive from Sussex centurion Rory Burns.
But there was time for Parnell to enjoy his third scalp and he ended the day with figures of 12-3-38-3 as Surrey closed on 213-6.
It followed on from his 4-23 and useful runs in both innings against Hampshire and any ring rustiness from not playing red ball cricket for 10 months has gradually disappeared.
Worcestershire resumed on 288-6 and Ed Barnard did not add to his overnight 63 before he was bowled by an inswinging delivery from Morne Morkel.
A square drive for four by Parnell off the same bowler lifted the total past the 300 mark.
Tom Curran struck in successive overs as Ben Twohig (2) was caught behind and Josh Tongue (5) holed out to short cover.
Parnell was last out after hitting six fours in his 104 ball knock when he pushed forward to spinner Amar Virdi and fell to sharp slip catch by Rikki Clarke.
He then immediately got to work with the ball and pushed Surrey onto the back foot.
Mark Stoneman (0) perished to a fine delivery which bowled him and the next delivery saw Barnard pull off a great catch at backward point to dispose of Dean Elgar (0).
Parnell could have picked up three wickets in the over but Daryl Mitchell at second slip was unable to hold onto a nick by Ollie Pope before he had scored.
Pope and Burns tried to rebuild the innings with a partnership of 97 in 24 overs before Parnell returned to strike for a third time.
This time Pope (48) went for a drive and keeper Alex Milton snaffled the chance away to his right.
Spinner Twohig got in on the act by bowling Will Jacks (17) after he had aimed a shot through mid wicket.
Burns was then joined by Rikki Clarke for a stand of 68 but two more wickets fell shortly before the close.
Rikki Clarke (33) was undone by a ball of extra bounce from Ross Whiteley and was caught behind.
Then Curran (0) nicked Tongue to first slip to leave the game evenly poised.
Joe Clarke did not field during the Surrey innings because of a back spasm.