Somerset 262 for 7 (Trego 140*, Wardlaw 3-55) beat Yorkshire 261 for 8 (Lees 62, Dibble 4-52) by three wickets
Peter Trego took his run tally in this season's Yorkshire Bank 40 to 705 with an unbeaten 140 as Somerset boosted their hopes of a semi-final appearance with a three-wicket win over Yorkshire at Taunton.
The visitors posted 261 for 8 after losing the toss, Alex Lees, Jack Leaning and Adam Lyth being the main contributors. Adam Dibble returned career-best List A figures of 4 for 52 runs, while Alfonso Thomas claimed 3 for 49.
Somerset reached their target with five balls to spare, Trego leading the way with an 85-ball ton to confirm his position as the competition's leading runscorer. He was well supported by Craig Kieswetter and Alviro Petersen, who made 51 on the final appearance of his spell with the county.
The result kept Somerset top of Group C with one fixture left against arch-rivals and fellow semi-final candidates Gloucestershire at Bristol on Monday week.
Yorkshire's innings was built around a third-wicket stand of 118 in 20 overs between Lees and Lyth, who came together with the total 39 for 2. Lees was first to his half-century, off 51 balls, with three fours and a six. Lyth soon followed, having faced 48 deliveries and hit seven fours.
It was 157 for 3 in the 27th over when Lees was yorked by Thomas and two overs later Lyth was also back in the pavilion, caught by Thomas at long-on off legspinner Max Waller, who went for 52 off his eight overs.
Leaning then assumed major responsibility for seeing the visitors to a challenging total, reaching the quickest fifty of the innings, off 42 balls, with four fours and a six. Strapping pace bowler Dibble accounted for him with a full toss in the penultimate over, having earlier dismissed Andrew Gale, Ryan Gibson and Rich Pyrah.
Marcus Trescothick got the hosts' reply going with a six off Iain Wardlaw, but departed for 10 to the next delivery, swishing his bat in frustration after driving a catch to mid-off. The skipper need not have worried. Trego and Kieswetter added 103 in 14 overs, mixing power and finesse in some sparkling strokeplay.
When Kieswetter fell to a catch at mid-off to give young Ryan Gibson a wicket, Petersen came in to join the run feast, striking two successive sixes off Gibson in the 21st over, on his way to a half-century off 51 balls.
For all that, it was Trego's day. Occasionally riding his luck, the allrounder blasted 19 fours and two sixes in a memorable exhibition that rendered a late flurry of wickets meaningless and took his average in 11 YB40 games to a staggering 88.12.