Somerset 285 and 204 for 6 (Goldsworthy 58, Lammonby 51) lead Surrey 428 (Sibley 100, Burns 75, Foakes 57, Aldridge 5-64) by 61 runs

Lawrence's offspin also accounted for Matt Renshaw, leg-before for 16 as he aimed a sweep from well across in front of his stumps. And, after a 58-run third wicket stand between Lammonby and Goldsworthy, the legbreaks of Steel provided further breakthroughs for Surrey in a lengthy spell by the 28-year-old from the Pavilion End either side of tea.

First he had Lammonby leg-before as he propped forward defensively and then Tom Banton, on 11, top-edged a cut to lob up a comfortable catch to Lawrence at backward point. Steel took two for 53 from his 21 overs.

It was Lawrence again who claimed Somerset's fifth wicket, turning one to take the edge of James Rew's bat to have the young left-hander superbly-held at boot level by Jamie Overton at slip for 22.

Goldsworthy's 131-ball resistance was finally ended by Gus Atkinson's pace and a thin edge through to Foakes and Somerset might have lost a seventh wicket when Kasey Aldridge, on nought, was dropped by Overton at slip off Lawrence despite a juggle with the ball after it had hit his wrist as he dived to his left.

At stumps, however, Aldridge had moved on to 20 and Somerset captain Lewis Gregory was also still there on 23 not out. The seventh-wicket pair have put on a creditable 42 so far, although Surrey remain heavy favourites to wrap up victory.

Surrey had earlier taken 24.2 overs to add a further 70 runs to their overnight score, with the whole-hearted Aldridge picking up three of the last four remaining wickets to finish with deserved figures of five for 64.

Clark was unlucky to be strangled down the legside on 13, in the day's sixth over, and Steel - who resumed on 35 - was brilliantly held by a leaping Lammonby at gully as he cut hard at paceman Aldridge.

Overton and Atkinson added 40 for the ninth wicket before Atkinson (15) was caught off Migael Pretorius aiming something violent and Overton's useful 35 came to an end when he under-edged a pull into his own stumps.