Jamie Porter found form in the Specsavers County Championship for the first time in 2019 as Essex's formidable fast bowler helped bowl Nottinghamshire out for 187.
Porter has enjoyed incredible hauls of over 50 wickets in the previous four campaigns, which included plundering 75 wickets in 2017's title winning season and 58 last year.
But having cumulative figures of two for 276 from the opening two games, against Hampshire and Surrey, he burst into life with analysis of four for 75, which included his 250th Championship notch in a typical destruction against Nottinghamshire.
Fellow bowlers Sam Cook, Peter Siddle and Simon Harmer all chipped in with two wickets-a-piece as Essex, who finished on 69 for no loss, dominated the first day's action at Chelmsford.
Zak Crawley's unbeaten half-century put Kent in control against Yorkshire.
Having bowled the White Rose out for 210 in the opening two sessions, Crawley finished unbeaten on 73 as Kent moved to 130 for four, just 80 behind.
Matt Milnes, with three for 63, and Harry Podmore, who took two for 33, were the pick of the home attack as the visitors succumbed inside 57 overs.
Centuries from Rory Burns and Dean Elgar put Surrey in a strong position.
Having won the toss on a day of unbroken sunshine, the visitors ran up 330 for six, with skipper Burns contributing 107 and Elgar making 103 against one of his former clubs.
Tom Alsop's second first-class century lifted Hampshire to a solid 291 for six against Warwickshire at Edgbaston.
After Hampshire chose to bat, Alsop compiled a career-best unbeaten 131 off 273 balls, hitting 21 fours, to steer his side away from uncertain positions at 44 for two and 171 for five.
— Surrey Cricket (@surreycricket) May 14, 2019
Worcestershire paceman Charlie Morris continued his fine form against Durham in Division Two.
Morris followed up his career best 7 for 45 against Leicestershire with six for 53 as Durham were bowled out for 273 in 92 overs.
But the Worcestershire attack were held up for a lengthy period by Jack Burnham, who missed the entire 2018 campaign through suspension after testing positive for cocaine in a third failed drugs test.
He top-scored with a resolute 76 to help rescue Durham from 14 for three.
Mohammed Abbas claimed four wickets on a topsy-turvy first day of Leicestershire's clash with Middlesex.
The Pakistani Test bowler looked a class above the rest in returning four for 57 to restrict the hosts to 325 for eight on a decent batting surface.
Nick Gubbins, debutant Tom Lace and George Scott – the latter's highest first-class score – all hit half-centuries for Middlesex.
Richard Gleeson took five wickets against his former county as Lancashire had the best of the opening day against Northamptonshire.
Gleeson finished with five for 63 as Northamptonshire were dismissed for 230 and by the close Lancashire had reached 29 for one in reply.
James Bracey's 152 helped Gloucestershire to a commanding 360 for six against Glamorgan.
Bracey shared as stand of 199 with Gareth Roderick, who made 88, as the visitors dominated the opening day.