FRIENDS PROVIDENT t20, Swalec Stadium: Somerset 92-3 (11.5 ovs) beat Glamorgan 116-7 (20 ovs) by seven wickets (D/L)
Trescothick has scored 471 runs in Twenty20 cricket this summer
Marcus Trescothick hit his fourth successive FP t20 half-century to lead Somerset to a rain-affected seven-wicket win over Glamorgan in Cardiff.
After slumping to 10-3, Glamorgan were grateful to a stand of 61 between Tom Maynard (39) and Ben Wright (22) for helping them post 116-7 from 20 overs.
Rain then saw Somerset handed a revised target of 92 to win in 15 overs.
And Trescothick hit an unbeaten 54 to see his side home with 19 balls to spare to go top of the South Group.
The former England opener's 50 came up off 29 balls and continued his excellent recent run of form, which started with 83 against Middlesex before making 78 against both Hampshire and Essex.
But all the hard work was done with the ball as Glamorgan struggled to get over their poor start.
Ben Phillips (2-20) did the early damage, bowling the dangerous Jim Allenby before having big-hitting Australian opener Mark Cosgrove caught behind.
Mark Turner caught Mark Wallace off his own bowling in between, giving Somerset an early grip on the contest that they refused to relinquish.
And although Maynard and Wright threatened a fightback, wickets fell regularly after they were parted, with Turner finishing with a Twenty20-best 3-25.
England one-day opener Craig Kieswetter's recent poor form continued as, after hitting James Harris for successive sixes, he was bowled off a bottom edge early in Somerset's reply.
But Trescothick ensured there would be no slip-up, hitting two sixes and six boundaries to see Somerset home and end Glamorgan's hopes of qualifying for the quarter-finals.
Somerset captain Marcus Trescothick told BBC Radio Bristol: "We're doing the good things well, trying to keep our energy levels up in what is an intensive period of T20 cricket.
"I thought our bowling performance was great, one of the best again.
"They keep improving and keep doing the job we're asking of them.
"In the last couple of games there have been good all-round performances in every aspect."