The ease with which runs are scored on this pitch, the presence of Marcus Trescothick and the fact that Yorkshire have not won a championship match for a year are the key factors that Anthony McGrath will have to mull over in timing his declaration this morning.

An innings of 152 by Joe Sayers ensured a healthy lead, but Taunton is an unforgiving square if the mathematics are awry. Sayers made his second championship century of the season, and Adam Lyth 71. This after Jacques Rudolph, scorer of 191 in the first innings, was out for a duck. Curiously, that occurred in the corresponding match last year, after he had made 155. On both occasions, Charl Willoughby had him caught in the slips.

Sayers was as watchful and relentless in his application as is expected from a Yorkshire opener.When he was bowled by Zander de Bruyn in the last over, he had made 152 off 283 balls, including 20 fours and a six.

Sayers was dropped badly by James Hildreth at gully before lunch, and Justin Langer was unsure which bowler to turn to while Jonathan Bairstow was striking 50 off 52 balls.

Eventually, the new ball, or tiredness, or both, accounted for Sayers. He did not manage to pass the highest score of his career, 187, but he has certainly given his side as good a chance as they will have had to gain their first victory of the season. A target of between 450 and 480 would seem to be the most realistic figure for Yorkshire to leave Somerset if they do not declare overnight.

Somerset's first innings had ended somewhat predictably in the morning when Willoughby, who basically plays the same shot to every ball - a step back to leg and a swing of the bat that, if he makes contact, sends the ball somewhere between backward point and mid-off - was taken by Bairstow off the bowling of Matthew Hoggard, who finished with five for 83. Not bad on this bland pitch for a bowler who has supposedly lost his nip.

Yorkshire: First Innings 438 (J A Rudolph 191; D A Stiff 4 for 92)
Second Innings
J A Rudolph c Trescothick b Willoughby 0
J J Sayers b de Bruyn 152
*A McGrath b Willoughby 25
A Lyth c Kieswetter b Stiff 71
A W Gale c Trescothick b Thomas 16
J M Bairstow not out 54
Extras (b 1, lb 2, nb 8) 11
Total (5 wkts, 92.1 overs) 329
Fall of wickets: 1-0, 2-58, 3-181, 4-221, 5-329.
Bowling: Willoughby 19-6-39-2; Thomas 13-1-63-1; Caddick 13-4-29-0; Suppiah 26-4-87-0; Trego 6-0-34-0; Stiff 11-0-52-1; De Bruyn 4.1-0-22-1.

Somerset: First Innings (overnight 326-9)
D A Stiff not out 6
C M Willoughby c Bairstow b Hoggard 6
Extras (lb 15, w 1) 16Total (79.4 overs) 326
Fall of wickets: 1-51, 2-64, 3-144, 4-215, 5-277, 6-287, 7-313, 8-315, 9-316.
Bowling: Hoggard 19.4-2-82-5; Shahzad 20-3-57-2; Patterson 14-2-55-1; Lee 13-1-63-2; Rafiq 13-0-54-0.
Umpires: T E Jesty and D J Millns.