Craig Kieswetter's career-best 93 helped Somerset to 402 on day one at Taunton and moved Division Two's top team five points nearer to promotion.

He shared a 130-run ninth-wicket partnership with Andy Caddick (43) to push the total on from 268-8.

Marcus Trescothick, Neil Edwards, Neil McKenzie and Ian Blackwell all hit half-centuries Huw Waters took 4-76.

In reply, Glamorgan closed on 55-1, Kieswetter catching Gareth Rees for seven off Charl Willoughby's bowling.

Somerset were asked to bat on a green-looking wicket by Mark Wallace, taking charge of Glamorgan for the first time with David Hemp missing the game because his wife was close to giving birth.

However, there were three figures on the board before the visitors struck, Trescothick trapped in front of his stumps by Alex Wharf for 52.