Sussex's bid for a hat-trick of 40 overs titles suffered a setback today after they were beaten by five wickets in a high-scoring game against Somerset at Taunton.

The Sharks looked in charge after scoring 291-8 from their 40 overs after they were put in before reducing Somerset to 109-4 in the 19th over with Marcus Trescothick (61) among those back in the pavilion.

But fifth wicket pair James Hildreth and 19-year-old Jos Buttler turned the game on its head with a scinitliating stand of 158 from 99 balls as the Sharks' attack was run ragged.

Neither offered a chance with Buttler hitting nine fours and a six in his 69 off 53 balls.

Hildreth did even better with an unbeaten 100 as Sussex lost by four wickets with nine balls to spare, their first defeat of the season in Group A of the Clydesdale Bank 40.

The Sharks had started well with Chad Keegan taking wickets with successive balls. Arul Suppiah was brilliantly caught one-handed at short mid-wicket by Ollie Rayner and Nick Compton playing across a straight ball first up.

Trescothick made 61 before he was caught at mid-wicket slog-sweeping Monty Panesar while Zander de Bruyn, who was dropped on nought, was leg before to Robin Martin-Jenkins.

But then the wheels came off as Hildreth and Buttler took advantage of perfect batting conditions and some unusually wayward Sussex bowling. Only Keegan and Panesar conceded less than seven runs an over and former Sussex all-rounder Damien Wright hit the winning boundary.

Hildreth finished 100 not out off 66 balls with 11 fours and three sixes.

Earlier Matt Prior (67), Michael Thornely (64) - his maiden one-day half-century - ansd Murray Goodwin (64) gave Sussex a platform for a total of more than 300 but they fell away in the last eight overs.

Only 63 runs were scored including their four-over power play and they lost six wickets during that time.