A VITAL last wicket stand of 50 between Craig Overton and Jack Leach gave Somerset a slight edge going into what is set to be an intriguing third day's play at the Cooper Associates County Ground.
Essex will resume in the morning on 10/0, requiring a further 245 to win on a testing pitch which led to 18 wickets falling on an eventful second day.
Craig Overton started an excellent morning for the hosts by picking up the key wicket of teenager Dan Lawrence who, having defied Jimmy Anderson and co on his way to an unbeaten 141 on Monday, was dismissed without scoring.
The key wicket remained that of Alastair Cook, who became the first player in the match to reach a half century with a single off Leach as the opener tried to rebuild with Ravi Bopara.
The latter failed to make an impact, becoming Leach's first victim of the season when he was bowled round his legs for eight, and Lewis Gregory then claimed the prize scalp when Cook played on to his stumps and was bowled having scored 52.
Buoyed by that crucial breakthrough, Gregory then picked up another as visiting captain Ryan ten Doeschate chipped to the grateful hands of James Hildreth at mid-wicket, and Roelof van der Merwe then joined in the fun as he dismissed Adam Wheater and Simon Harmer before lunch.
A first innings lead of 80 was secured as Leach and Jamie Overton picked up the final two Essex wickets, but Somerset failed to press home their advantage and lost Marcus Trescothick (5) and captain Tom Abell (0) early.
As in the first innings, Dean Elgar and James Hildreth combined effectively before falling in quick succession, with the opener trapped in front by Harmer and Hildreth caught by the same player from the bowling of Ravi Bopara.
Neil Wagner then dominated the afternoon session, running through the lower middle order to leave Somerset on 124-9 and requiring the tail to wag.
Craig Overton and Leach did just that, adding 50 before Wagner dismissed the former to pick up his sixth wicket, and Essex's opening pair of Alastair Cook and Nick Browne survived a testing seven overs before the close to leave the match tantalisingly poised.