Chris Benham secured Pro40 promotion with a career-best 158 against Glamorgan - the highest individual one-day score by a Hampshire batsman for ten years.
Benham's sensational 130-ball effort matched the 158 that Robin Smith made against Worcestershire at New Road in the 60-over Natwest Trophy a decade ago.
It was also the new Pro40 competition's highest individual score - surpassing the 152 made by Leicestershire's Darren Maddy against Surrey at the Oval six weeks ago.
The 23-year-old reached his first hundred since his maiden 122 against West Indies A from just 79 balls to set up a comfortable 151-run win that assured the Hawks of an immediate return to the top flight of the one-day league.
A year after Kevin Pietersen secured the Ashes with his 158 at the Oval, Benham displayed the sort of powerful top-order hitting the England man would have been proud of as the Hawks won county cricket's first play-off.
Benham has been threatening a big hundred for weeks and struck 21 fours as well as a powerfully pulled six that flew over the long, square leg boundary at the end of the second over from Andrew Davies.
He swept and reverse swept the spinners with precision and after reaching his fifty from 48 balls only needed another 31 to reach three figures, and a further 47 for the unchartered 150 before he was eventually bowled by a yorker in the penultimate over.
Benham and Michael Brown began the innings with a century-stand for the first wicket as the pair had done in the win against the West Indies A five weeks earlier.
Brown was preferred to Jimmy Adams after Michael Carberry (groin) failed a fitness test and struck 29 from 30 balls in only his seventh one-day appearance in three seasons with Hampshire.
His 106-run first-wicket stand with Benham provided the basis of the Hawks' Pro40-best 265.
It was also Hampshire's highest one-day total since Benham scored an unbeaten 73 in a 165-run win against Glamorgan in the 50-over C & G Trophy three months ago.
There was a sense of dj vu this time but not for Benham, who punched the air and raised both arms in the direction of the Hampshire balcony after reaching his hundred by sweeping Robert Croft for his 16th four in front of a 4,000-plus crowd that included his parents.
Benham's blossoming in the second half of the season has been one of several Hampshire positives this year, and his fifth-wicket partnership with Dimitri Mascarenhas took the game away from the visitors.
Together they put on 51 in just five overs before Mascarenhas holed out for a 17-ball 30 that included two sixes over mid-wicket against Dan Cherry and a straight maximum against James Franklin.
Shane Warne had lost the toss but was delighted with a total that left Glamorgan needing more than six runs an over to retain their first division status.
Anything other than a Hawks win did not look likely when James Bruce, who become Hampshire's fifth player in six weeks to be awarded his county cap during the interval, dismissed Richard Grant with the second ball of the Welsh county's reply.
Glamorgan opener David Harrison blasted three fours in the first over but when he was caught at mid-wicket the visitors soon slid to 89-9.
Bruce, bowling on the same wicket used for Hampshire's championship draw against Lancashire, finished with 3-48 as Glamorgan were bowled out for 114.
But even more encouraging was Sean Ervine's season-best 4-24, a haul that included a brilliant catch by Lamb at gully to dismiss Glamorgan captain David Hemp.
Fittingly, Warne completed the rout.
Hampshire bowling: Bruce 6.1-1-48-3, Ervine 8-0-24-4, Taylor 3.5-1-9-1, Warne 4.2-1-16-2, Udal 3-0-13-0