A brilliant unbeaten 126 from Craig Kieswetter put Somerset clear at the top of Yorkshire Bank 40 Group C after they beat Gloucestershire Gladiators by seven wickets with 39 balls to spare at Taunton.
Gloucestershire posted a challenging 263 for eight a total based on an unbeaten 131 from Michael Klinger but he had little support from his team-mates, Chris Dent the next highest scorer with 32.
Marcus Trescothick scored 39 to help put on 87 for the first wicket, after which Kieswetter and Peter Trego, who made 59, took the hosts to 182 in the 22nd over by which time Somerset all but had the game in the bag.
At the start of the afternoon Klinger, who was dropped at slip by Trescothick before getting off the mark, made 23 with Hamish Marshall, before Marshall was caught by Trego at short midwicket off Steve Kirby.
Klinger and Chris Dent added 71 before Jamie Overton returned and accounted for Dent with his first delivery, caught by wicketkeeper Kieswetter for 32.
But Klinger was enjoying himself and reached a run-a-ball fifty, though wickets continued to fall at the other end.
Max Waller looked dangerous and was rewarded when he bowled James Fuller with a quicker ball.
There was further joy for Somerset when Alviro Petersen came on at the River End and first ball had Ian Cockbain caught by Waller at mid-on for 12.
Klinger had moved on to 65 when he was put down for a second time, this time at deep mid-off by Overton.
The opener brought up the 150 with a lofted four to long-off from Petersen, to take him on to 75, but two runs later he was missed for a third time, this time by Craig Meschede who failed to hang on to a tough caught and bowled chance.
Klinger went to his century when he clipped Kirby off his legs to the midwicket boundary.
The fifth wicket pair had added 71 to take the total on to 203 when Alex Gidman was caught at deep midwicket off a Kirby full toss for 19.
Klinger remained at the crease until the end of the innings by which time he had moved on to 131 off 126 balls, including 14 fours and two sixes, as Gloucestershire ended on 263 for eight.
The Somerset reply started quickly as Trescothick and Kieswetter hurried the hosts to 50 off the last ball of the fifth over.
Trescothick was missed on 35 but four runs later was caught at short cover by Klinger off Benny Howell with the score on 87 in the ninth over.
Kieswetter went to his fifty with a single off Young to short cover off 37 balls including six fours and a six.
Trego wasted no time in joining the run spree and hit off spinner Tom Smith high on to the Old Pavilion roof and went to his fifty off 38 balls, including six fours and a six with two to deep backward point off Dent in the 18th over.
Kieswetter carried on with the plunder and drove Smith high back over his head in his next over.
The second-wicket partnership was worth 95 when Trego drilled a ball from Dent to short extra-cover, where Klinger held on to the sharp chance.
Petersen stayed a short while before he was caught at deep midwicket by Howell off Fuller with the total on 202.
Kieswetter went to his century with two to backward square leg off Fuller, the 11th List A ton of his career, which came off 88 balls with nine fours and three sixes.
Kieswetter hit three sixes off the 33rd over, bowled by Howell, to level the scores and Nick Compton rounded things off with a four off Smith off the third ball of the next over.
Kieswetter ended unbeaten on 126 which included 10 four and six sixes, while Compton was not out 22 as Somerset reached 267 for three.