A brilliant unbeaten 126 from Craig Kieswetter put Somerset clear at the top of Yorkshire Bank 40 Group C after they beat Gloucestershire by seven wickets with 39 balls to spare.
Gloucestershire posted a challenging 263-8, 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.
And it could have been worse for the visitors as Klinger was dropped three times during his innings.
Firstly, he was put down at slip by Marcus Trescothick before getting off the mark before he moved on to 65 when he was put down for a second time, this time at deep mid-off by Jamie Overton.
The opener then brought up the 150 with a lofted four to long off from Alviro 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 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 263-8.
The Somerset reply started quickly as Trescothick and Kieswetter hurried the hosts to 50 off the last ball of the fifth over.
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.
Kieswetter hit three sixes off the 33rd over by Benny Howell to level the scores and Nick Compton rounded things off with a four 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 267-3.