WORCESTERSHIRE'S Cheltenham & Gloucester Trophy dreams were shattered by a fine century from Keith Parsons who powered holders Somerset to a deserved four wicket win at Taunton.

Parsons stole the show as he helped his side book a home semi-final showdown against Kent with 15 balls to spare.

For Worcestershire it was a bitterly disappointing result, particularly as they had already beaten Somerset on three previous occasions in one-day matches this season.

They also failed to capitalise on the home side's injury problems which were increased early in the game when England star Marcus Trescothick suffered a badly broken left thumb while fielding.

Parsons, however, eased the pain by deservedly picking up the man-of-the-match award for scoring a one-day best 121, taking two wickets, holding two catches and being responsible for one of the County two run-outs.

Facing a victory target of 272, and with Trescothick only set to bat in a dire emergency, Parsons firstly put on 51 in six overs with Michael Burns, a further 58 in eight overs with Ian Blackwell and then another crucial 106 in 21 overs with Malvern-born Rob Turner.

By the time he was out, Parsons had clubbed one six and 15 fours off 100 balls in 133 minutes.

"I don't think he would have batted any better than that in his career," said Worcestershire's Director of Cricket Tom Moody, who added: "He turned it on. Full credit it to him to do it in such a big game."

Once Parsons and Turner were out, Somerset were guided to victory by Keith Dutch and Matthew Bulbeck.

Earlier, Worcestershire, after being put in, made such an impressive start to their innings that they looked likely to make far more than their score of 271 off 49 overs.

Somerset, however, staged a spirited fightback sparked by Parsons bowling Graeme Hick for 39.

It ended an 81-run partnership in 12 overs with Vikram Solanki which began after opener Stephen Peters had been trapped leg before by paceman Steffan Jones for 18.

Hick's contribution, however, was painful in more ways than one for Somerset. Indeed, it was his fierce cover drive which led to Trescothick suffering his broken thumb.

After stopping the ball low down, he knew immediately that he had a serious problem and headed off to the pavilion -- and a lengthy spell on the casualty list.

Trescothick's cruel setback, however, appeared to put more bite into his side's fightback which gathered momentum when Solanki's attempted pull off Burns ended up in Blackwell's hands at mid-on. His 53 included 10 fours off 57 balls.

Once Solanki had gone Somerset's successes became more frequent, although Ben Smith was undefeated on 85 containing eight fours off 104 balls.

Those around him, however, were less successful with David Leather-dale, Gareth Batty, Kabir Ali, Stuart Lampitt and Matt Mason failing to reach double figures.