|Specsavers County Championship Division One, Headingley, day one|
|Yorkshire 145: Bresnan 38*; Allenby 3-16, Overton 3-32|
|Somerset 107-1: Rogers 58*, Trescothick 45*|
|Somerset (3 pts) trail Yorkshire (0 pts) by 38 runs|
Somerset dented Yorkshire's bid for a third consecutive County Championship title and boosted their own hopes of a first county crown by bowling out the hosts for 145 on day one at Headingley.
Tim Bresnan (38 not out) top-scored for Yorkshire, who began the day one point behind Division One leaders Middlesex.
Craig Overton (3-32) and Jim Allenby (3-16) starred for the visitors, who started 22 points off top spot.
Somerset ended a dominant first day by reaching 107-1 at the close.
Jack Brooks trapped opener Tom Abell lbw for a duck in the second over of Somerset's reply, but veteran pair Marcus Trescothick (45 not out) and Chris Rogers (58 not out) shared an unbroken stand of 107, which was only halted when bad light ended play seven overs early.
Second-placed Yorkshire, who are unable to call upon England pair Joe Root and Jonny Bairstow for their final two games of 2016, won the toss and chose to bat first.
But that decision backfired as they made their lowest total in a completed Championship innings this season, lasted only 61.2 overs and failed to collect any batting bonus points.
Seven home batsmen were caught by the wicketkeeper or at slip as the accuracy of Somerset's seamers was rewarded with a steady stream of success.
Jake Lehmann (31) was dropped on nought by Lewis Gregory at slip and added 47 for the fourth wicket with captain Andrew Gale (29) before he miscued a pull off Peter Trego in the final over before lunch.
That started a collapse of six wickets for 36 runs, with Bresnan left unbeaten as Yorkshire were bowled out before tea.