A meticulous six-hour hundred from Mark Ramprakash, his third of the campaign, helped Surrey to a tiny lead, but they needed a bigger one to put pressure on Middlesex today. Surrey are the only side who could still win the match, but it appears destined to drift towards stalemate.

Ramprakash's fourth hundred in eight championship matches against his former county means that he has taken more than 1,000 runs off them at an average of 91. With five centuries against Surrey in 15 encounters, it is true to say he is strongly motivated by London derbies.

Moments after being dropped at short leg off Shaun Udal, he was beaten by Murali Kartik's quicker ball, his 136 having spanned 306 balls. The Indian obtained some turn to finish with five wickets.

Middlesex supporters were entitled to wonder why Kartik, having got Ramprakash out coming round the wicket, had persisted with a negative over-the-wicket angle of attack against the former England batsman. In doing so, he prevented Surrey from scoring quicker, but reinforced the notion that Middlesex were less interested in trying to win the game than in avoiding defeat.

On a slow, used pitch, the accurate Kartik went for only one and half runs per over. It was left to the quicker bowlers, however, to make the initial breakthroughs, Chris Silverwood producing a beauty that went up the hill to have Mark Butcher caught at first slip. That ended a third-wicket alliance with Ramprakash of 101 in 40 overs.

When Ramprakash and Usman Afzaal, with a positive 84-ball fifty, then put on 109 in 33 overs for the fourth wicket, Surrey would have been eyeing up a three-figure first-innings lead. But after Steve Finn bounced Afzaal out, tempting him to hook to a deepish mid-wicket position where Gareth Berg took a fine catch, Kartik mopped up the tail.

Ramprakash did not reach his century without some good fortune. The first of three fours in four balls off Finn that took him from 89 to 101 was inside-edged perilously close to leg stump. Another faint inside edge was all that saved him from being stumped when he went down the pitch to Kartik.

In all, he hit 17 fours, the best an inside-out drive through extra cover off the left-arm spinner when he used his feet.

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) 16
Total (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.