Centuries from Jimmy Adams and John Crawley flayed the champions, Nottinghamshire, as the Hampshire captain, Shane Warne, put his feet up on his return to County Championship action yesterday.
Adams was 123 not out with Crawley unbeaten on 106 as Hampshire reached 303 for 1 at the close of day one in their First Division match at Trent Bridge.
England's Ed Joyce, who injured his ankle in a one-day international against Sri Lanka last month, looked in fine touch as he reached 158 not out for Middlesex, who ended day one on 344 for 5 against Warwickshire at Edgbaston.
In the Second Division, Anthony McGrath hit 140 not out as Yorkshire were bowled out for 339 by Durham, who had reached 64 for 2 by the close.
At Northampton, Alistair Brown hit a typically flamboyant 113 before Surrey were bowled out for 328, Matt Nicholson taking four wickets. Surrey then picked up three quick wickets as the hosts struggled in reply.
Derbyshire closed on 374 for 9 against Somerset at Taunton, with the Australian Marcus North clubbing a century.
Another overseas player, Hilton Ackerman, smashed 177 not out as Leicestershire ended the first day on 354 for 6 against Glamorgan at Cardiff.
On the second day at Bristol, Andy Flower's century helped Essex reach 265 for 4 in reply to Gloucestershire's 394 all out.