Matt Prior, who could yet play for England in the forthcoming ICC Champions Trophy as a specialist batsman, made a match-winning 137 off 123 balls to give Sussex a victory over Somerset that was so well plotted as to never appear in doubt.

His timing, on a pitch lacking in pace, brought him 12 fours and three sixes. Even though he was out at the start of the final over, Sussex had the requisite wickets in hand.

This was Prior's highest score in one-day cricket this season, although he has three centuries in the LV County Championship. The importance that is attached nowadays to wicketkeepers making runs was emphasised by both in this match being asked to open the batting. Craig Kieswetter, out cheaply yesterday, will, nevertheless, be competing with Prior for international recognition in future.

Two easy pick-ups into the crowd of about 5,000 also showed what an unenviable task a little-used spinner such as Arul Suppiah, the Malaysia-born all-rounder, had in bowling to Prior. His century came from 84 balls and he put on 99 runs in 16 overs with Luke Wright, who contributed 40 before he was caught at long-on.

Sussex needed four to win off the final over. Alfonso Thomas bowled Prior with his first ball, but the century-maker was succeeded at the crease by Dwayne Smith, the former West Indies all-rounder, making his first appearance for Sussex as a Kolpak player. Smith knows a thing or two about how to play this game and three runs to him, and a cover-driven four by Murray Goodwin, brought victory with two balls to spare. The counties meet again next week in the Horsham Festival, this time in the County Championship.

Somerset, who preferred Suppiah's left-arm spin to that of Ian Blackwell, who is in and out of the side this season, reached a respectable total largely through the efforts of Marcus Trescothick, who made 91 off 94 balls after being dropped by Chris Adams, the Sussex captain, at slip off James Kirtley when he had made only one. Strange as it may seem, this was not one of Trescothick's more memorable innings in that it lacked the customary dominance of his straight and square driving. He hit nine fours, while Zander de Bruyn managed only two in his unbeaten 70.

Suppiah, who has been unlucky not to have played more first-team cricket this season, struck 30 off 12 balls, with two sixes and two fours.

Justin Langer drove Robin Martin-Jenkins for a straight six and was bowled next ball, and Peter Trego was brilliantly held by Chris Liddle in his follow through. All in all, Somerset were about 20 runs short of the kind of total they would have wanted, even though they were put in.

Scoreboard

Somerset
M E Trescothick c Smith b Yardy 91
†C Kieswetter c Smith b Kirtley 16
P D Trego c and b Liddle 16
*J L Langer b Martin-Jenkins 6
Z de Bruyn not out 70
J C Hildreth c Smith b Yardy 1
A V Suppiah c Prior b Wright 30
O A C Banks b Wright 0
A C Thomas not out 5
Extras (b 2, lb 1, w 4) 7

Total (7 wkts, 40 overs) 242

A R Caddick and C M Willoughby did not bat.

Fall of wickets: 1-29, 2-48, 3-59, 4-184, 5-188, 6-231, 7-231.

Bowling: Martin-Jenkins 8-0-45-1; Kirtley 6-1-41-1; Liddle 4-0-23-1; Hamilton-Brown 8-0-39-0; Yardy 8-0-62-2; Smith 3-0-14-0; Wright 3-0-15-2.

Sussex
M H Yardy lbw b Trego 20
†M J Prior b Thomas 137
L J Wright c De Bruyn b Thomas 40
*C J Adams c De Bruyn b Trego 36
M W Goodwin not out 5
D R Smith not out 3
Extras (lb 3, w 2) 5

Total (4 wkts, 39.4 overs) 246

C D Hopkinson, R J Hamilton-Brown, R S C Martin-Jenkins, C J Liddle and R J Kirtley did not bat.

Fall of wickets: 1-64, 2-163, 3-237, 4-239.

Bowling: Willoughby 8-1-43-0; Caddick 8-0-50-0; Trego 8-0-47-2; Thomas 7.4-0-48-2; Suppiah 4-0-34-0; Banks 4-0-21-0.

Umpires: J H Evans and J W Holder.