A comfortable six-wicket win over the Unicorns saw Somerset back to the top of Group C in their Clydesdale Bank 40 clash at Taunton on Sunday.
Michael Thornely became the first Unicorns player to score a CB40 century this season as the visitors posted 208-5 after winning the toss.
But the target never looked too challenging for a strong Somerset batting line-up, who cruised to victory with five overs to spare.
Opener Thornely remained unbeaten on 105 at the end of the 40 overs, taking 115 balls to reach his total with 11 fours.
Captain Keith Parsons contributed 38 to the Unicorns' score, the former Somerset favourite putting on 53 for the fourth wicket with Thornely before he holed out to deep midwicket in the 26th over to make it 115-3.
Trescothick and Kieswetter set about the run-chase with gusto but the latter drove Luis Reece to cover while on 45.
Trescothick was bowled trying to reverse sweep spinner Bradley Wadlan soon after, after making a 42-ball 53 that included seven fours.
James Hildreth moved to his half-century off 50 deliveries, supported by Nick Compton, who celebrated his first county cap with 25 off 43 balls.
Compton was bowled by Andy McGarry with 27 runs still needed but Jos Buttler smashed 23 off just eight balls, sealing the win when he clobbered Glen Querl for a huge six over midwicket.
The win left Somerset requiring just one win from their two remaining games to all but see them through to the semi-finals.