County Championship D2, Taunton (day three, close): Somerset 275 & 213-6; Yorkshire 512
Yorkshire seamer Steve Kirby added to his five first innings wickets by taking 4-48 in Somerset's second innings, leaving the hosts staring at defeat.
Kirby took wickets at crucial intervals. His first three victims had all had decent starts - Peter Bowler the best of them with 58 - before falling to the red-haired quick.
At the start of the day, Yorkshire had added 103 from the last four wickets mainly due to Andy Gray's 104.
Nixon McLean and Simon Francis each finished with three wickets.
In Somerset's second innings, Chris Silverwood had the first breakthrough by having Matthew Wood caught by Craig White.
A stand of 87 between Bowler and Jamie Bryant (45) was ended by Kirby and the bowler did not look back after that.
Somerset: P D Bowler, M J Wood, J D C Bryant, J Cox, M Burns (Capt), I D Blackwell, R J Turner (Wkt), A W Laraman, N A M McLean, P S Jones, S R G Francis.
Yorkshire: M J Wood (Capt), S P Fleming, C White, M J Lumb, Yuvraj Singh, R J Blakey, S M Guy (Wkt), A K D Gray, C E W Silverwood, R J Sidebottom, S P Kirby.