Sussex paceman Henry Crocombe also took a hat-trick against Somerset in the last round of fixtures Rothesay County Championship, Division One, Ambassador Cruise Line Ground, Chelmsford (day two) Sussex 275: Leaning 60; Porter 4-44 & 90-4: Coles 29*; Harmer 2-19 Essex 177: Allison 56; Crocombe 5-39 Sussex (4 pts) lead Essex (3 pts) by 188 runs.

Henry Crocombe claimed his second hat-trick in a week, and third five-wicket haul of the season, to leave Essex's batting in total disarray on an incredible evening of tumbling wickets at Chelmsford. The 24-year-old seamer, who leaves Sussex for Surrey at the end of the season, had never taken three wickets in successive balls before running through Somerset's tail at Hove last week.

For an encore, he helped reduce Essex from 171-3 to 177 all out in the space of 26 balls, his five wickets coming in 14 deliveries without conceding a run. He finished with 5-39. Essex had been progressing serenely after tea on the second day of the County Championship match when Charlie Allison became Crocombe's first victim after a tidy 56. That wicket exposed the tender underbelly of Essex's batting and revived fears of a battle against relegation in the run-in to the Division One season.

The collapse gave Sussex an unexpected first-innings lead of 98 after they had taken their score to 275 in the morning, thanks largely to the re-engaged Ari Karvelas thrashing six fours in a breezy 38 from 44 balls. However, they lost Tom Haines, Tom Clark, Charlie Tear and Oli Carter second time round in extending their advantage to 188 as 11 wickets fell after tea.

Karvelas was not finished when he was last man out in Sussex's first innings and, taking the new-ball, separated the Essex opening pair with an angled delivery into Paul Walter's stumps. Tom Westley then had a rush of blood and, in attempting to heave Jack Carson over midwicket, was also bowled.

With the sun breaking through and a drying wind, the wicket flattened out and batting seemed to be becoming easier than on day one. At that stage there was no hint of what was to come. Indeed, Essex reached three figures for two wickets down in 32 overs, 12 quicker than Sussex, the milestone reached with a reverse sweep for four by Allison off Carson.

Allison contributed 38 of a 58-run stand with Dean Elgar before James Coles found extravagant turn with his third ball to bowl Elgar. Allison's eighth boundary, a drive off Tom Haines, took him to fifty from 60 balls, but he became bogged down, adding only six more from a further 26 balls before he was lbw playing around one from Crocombe.

Then came the carnage. Almost immediately Michael Pepper attempted to sweep Coles and went lbw. Then Crocombe took centre stage. Simon Harmer and Zaman Akhter were both trapped lbw to the first two balls of Crocombe's ninth over before Shane Snater played over the third and lost his leg stump. Mitch Killeen had been recalled from a loan spell with Gloucestershire to replace Sam Cook, who was called up by England mid-match. Killeen lasted seven balls before he stepped back to try and cut Coles and was bowled.

And it wasn't long before Jamie Porter became the sixth player to lose his stumps in the innings, wicket number five for a rampant Crocombe. Essex took an hour to wrap up the last three Sussex wickets despite Cook removing Dom Goodman playing down the wrong line to the first ball of the morning. That only brought in Karvelas to help Sussex add 62 runs and claim a batting point.

Karvelas was playing a first-class game for the first time in a year after being released by the club. The South African seamer has since worked as a coach in the Sussex academy and been re-signed on a short-term contract to cover injuries and England call-ups.

Jack Leaning put on 36 for the ninth wicket with Karvelas before falling to another catch behind off Akhter for a 110-ball 60. Karvelas was finally out when he edged Porter to give Pepper a fifth catch in the innings and Porter his 600th first-class wicket in figures of 4-44.

ECB Reporters' Network supported by Rothesay. Northants gain edge against leaders Durham Hampshire make Kuggeleijn U-turn after criticism Notifications, social media and more with BBC Sport