Essex 50 for 1 trail Worcestershire 266 D'Oliveira 68, Taylor 62*, Porter 5-52) by 216 runs
Jamie Porter blitzed a hole in the Worcestershire upper-order to return his second Vitality County Championship five-wicket haul of the season before Essex let slip their early advantage on day one.
Essex had Worcestershire 10 for 4 inside five overs - Porter and Sam Cook sharing the four wickets in a 13-ball spree - then 46 for 5 in 12 overs, before the tail wagged and the visitors reached a more respectable 266 all out shortly after a late tea.
Porter, the joint leading wicket-taker in Division One, finished with 5 for 52 from 17 overs of controlled aggression on a flat Chelmsford pitch that later played to the strengths of Simon Harmer. The South Africa off-spinner marked his 100th red-ball appearance for Essex with a trio of lower-order victims for figures of 3 for 103.
Captain Brett D'Oliveira sparked the Worcestershire recovery after electing to bat with a patient 136-ball 68, supported in important stands by Ethan Brooks (46) and Tom Taylor (62 not out), the later aided by Amar Virdi in keeping Essex in the field with a last-wicket stand of 64. Essex had knocked off 50 of the deficit for the loss of Dean Elgar in 19 evening overs.
Porter struck with his ninth ball when he got one to jag in and take Jack Libby's off stump. After opening-ball partner Cook removed Gareth Roderick in the next over, lbw to one that thudded into his back foot, Porter claimed two wickets in three deliveries.
Both wickets fell to catches behind, Rob Jones playing down the wrong line and taken low down by Michael Pepper, and Adam Hose followed to a tentative push against one that swung away.
Two partnerships involving D'Oliveira went some way to repairing the damage as the Kookaburra ball lost its initial hardness. He enjoyed a seven-over interlude between wickets while adding 36 with Kashif Ali. Ali had watched three colleagues depart, but then hit his stride with five boundaries in a run-a-ball 24 before he dragged on when Porter returned after a brief rest.
D'Oliveira next found support in a 72-run sixth-wicket stand with Brookes. But the captain was fortunate to survive a sharp chance to Elgar at slip in the over before lunch when Matt Critchley got a second successive ball to jump almost vertically off the pitch.
Brookes, meanwhile, was no respecter of reputation and went after Harmer, twice reverse-sweeping the off-spinner to the boundary. He accelerated after lunch, adding three more to his collection of nine fours in a 73-ball 46, before dangling his bat and becoming Porter's 39th scalp of the season.
Harmer finally joined the party in his 14th over when he induced Logan van Beek to drive lazily straight back to him. He followed up four overs later by ending D'Oliveira's 59-run eighth-wicket stand with Taylor, trapping him lbw, and then accounting for Joe Leach by the same method shortly afterwards.
However, from 202-9, the last-wicket pair collected a hitherto unlikely batting point. Virdi played particularly straight, hitting the majority of his 42 runs in the arc between long-on and long-off, including two towering sixes off Harmer. The innings came to an end five overs before the new-ball was due when the Surrey loanee clipped Shane Snater to square leg.
Essex lost Elgar lbw to Taylor to the last ball before the close after he and Robin Das had been largely untroubled. They will have Jordan Cox available to bat later after he was released by England once the team had been confirmed following the toss at Lord's, though Noah Thain had been named in the initial Essex XI in case Cox was retained.
