Surrey 24 for 0 trail Somerset 429 (Clark 3-75) by 405 runs
Somerset will qualify for the Division One stage of this summer's new-look LV= Insurance County Championship format if they avoid defeat against Surrey at the Kia Oval this week and, on a weather-reduced second day, the Group Two leaders took significant steps towards that aim by reaching 429 all out in their first innings.
Late afternoon rain then caused the last 37 overs of the day to be lost after Surrey's openers Rory Burns and Mark Stoneman had reached 24 for no wicket in reply in the final conference-stage match.
Somerset's lower order had earlier batted well against Surrey's spin trio of R Ashwin, Amar Virdi and Dan Moriarty on a slow surface, with Indian Test offspinner Ashwin toiling through 43 overs in all for his eventual 1 for 99 and Virdi emerging as the most successful with figures of 3 for 86. Moriarty finished with 2 for 109.
Resuming on 280 for 6, Somerset added 149 more runs in 50.5 overs of further hard graft, securing a third batting bonus point in the process. It completed a fine collective performance and the overnight not out pair of Roelof van der Merwe and Ben Green took their seventh wicket stand to 61 in 28 overs before Surrey offspinner Virdi made the breakthrough.
Virdi, somewhat surprisingly, had to wait 90 minutes for his first bowl of day two and, with his second ball, he turned one to have Van der Merwe adjudged caught at short leg for 41.
Green also batted with great self-discipline for 43, from 114 balls, before Virdi had him caught at slip and, soon afterwards, Jack Leach advanced to hit Virdi high over long-on for six.
There were also two leg-side sixes from Marchant de Lange, launched powerfully off Ashwin and Moriarty, before on 29 he edged left-arm spinner Moriarty to give Rikki Clarke his second catch of the day at slip.
It was close to 3pm when Somerset's first innings finally closed, Jack Brooks mishitting Moriarty to Ashwin at point to go for 9. Leach remained unbeaten on 28, a stout 67-ball effort, but there was only time for six overs of Surrey's first innings before the rain came.