Somerset 257 for 5 (Abell 79) trail Hampshire 338 (Ervine 103, McLaren 61, Leach 6-108) by 81 runs
Tom Abell gave a reminder of his immense promise as Somerset responded positively to Hampshire's first innings score of 338 on the second day of the Specsavers County Championship match at Taunton.
The 22-year-old opener, who has not enjoyed the best of seasons in four-day cricket, hit 79, off 132 balls with 11 fours, sharing an opening stand of 87 with Marcus Trescothick, who made 36, as the hosts closed on 257 for 5.
Peter Trego contributed 42, James Hildreth 40 and Jim Allenby 37 not out, but none of the home batsmen were able to push on to the big score needed to establish control of the game.
Earlier, Jack Leach had finished with 6 for 108 as Hampshire added 57 to their overnight score of 281 for 6, David Wainwright making a valuable 35 not out. The left-arm spinner now has 43 first class wickets to his name this season.
The ball turned from ball one of the day, but more for the Somerset spinners, whose counterparts were unable to settle on the right pace to exploit the pitch to the full.
From an overnight 281 for 6, the visitors slipped to 303 for 9 before a valuable last-wicket stand of 35 between Brad Wheal and David Wainwright, who contributed 35 not out with the ball deviating considerably for Leach and fellow left-arm spinner Roelof van der Merwe.
Leach sent back Lewis McManus, Mason Crane and Wheal. But Hampshire could feel satisfied with their efforts as both sides collected three bonus points from the innings.
Somerset were left with nine overs to bat before lunch and reached the interval on 40 without loss, Trescothick and Abell surviving comfortably against six overs of seam and three of spin.
Trescothick looked in little bother until trying to hit Wainwright over the top and falling to a catch at long-on. His disappointment was matched by that of Chris Rogers, who had made only 11 when giving legspinner Mason Crane the charge and offering a leg-side stumping to McManus.