Adam Hose made a career-best 266 during a third-wicket stand of 395 with Jake Libby as bottom-of-the-table Worcestershire dominated day one of their Rothesay County Championship clash with Hampshire.
Hose smashed 31 fours and seven sixes off 253 deliveries, while stand-in captain Libby passed 10,000 career runs on his way to an unbeaten 137.
The Pears, who have won only once all season, reached 463-3 at stumps in the Division One match at Southampton.
Centuries from Dom Sibley and Sam Curran helped reigning champions Surrey take control against Durham.
Opener Sibley remained unbeaten on 169 and Curran contributed 108 off 124 balls in a score of 407-3, with captain Rory Burns having registered 55 at the start of the innings at The Oval.
Dan Lawrence will resume alongside Sibley on 58 for the second-placed hosts.
Half-centuries from James Rew, Tom Abell and Tom Banton dug Somerset out of trouble against leaders Nottinghamshire at Taunton.
The hosts slipped to 46-3 after winning the toss before Rew (58), Abell (64) and Banton (57 not out) guided them to 275-6 at the close.
Essex captain Tom Westley made 107 as his side closed on 248-3 away to relegation rivals Yorkshire.
Westley hit 12 fours in 239 balls and shared 198 for the second wicket with former South Africa captain Dean Elgar, who was dismissed for 94.
Warwickshire opener Rob Yates made 93 in a total of 372-7 against third-placed Sussex at Hove.
Sam Hain and Ed Barnard posted 87 and 66 respectively for the visitors, while Henry Crocombe took 3-73 for the hosts.
In Division Two, Middlesex opener Sam Robson recorded his first County Championship hundred of the season as his side ended on 336-5 against table-topping Leicestershire.
Robson hit 133 in a first-wicket stand of 173 with Joshua De Caires (76), while Roman Walker took 3-57 for the home team.
Ben Compton celebrated being handed his county cap and a new three-year contract by making 66 during Kent's clash with Northamptonshire at Canterbury.
The division's bottom side were 325-4 at stumps, with Tawanda Muyeye hitting 58 and captain Daniel Bell-Drummond not out on 66.
Landmark centuries from Keaton Jennings and Chris Green revived Lancashire against Derbyshire at Chesterfield.
Jennings passed 12,000 first-class runs on his way to 106 while Green celebrated his maiden red-ball hundred as Lancashire recovered from 132-6 to 367 all out.
James Bracey's unbeaten 57 backed up half-centuries from captain Cameron Bancroft and Zaman Akhter as Gloucestershire closed on 279-7 against Glamorgan at Cardiff.
Timm van der Gugten trapped Bancroft lbw for 50 and later dismissed Akhter by the same method for 58. Mason Crane chipped in with three wickets.
