James Hildreth led the way with a century as Somerset gained maximum batting points on the opening day of the County Championship division one clash with Hampshire at Taunton.
But from a dominant 353 for three, the league leaders slipped to 408 all out.
Kyle Abbott claimed six for 84, four of his wickets coming with the second new ball.
Hildreth’s exquisite 105 was his first Championship hundred of the season. He shared a second-wicket stand of 178 with skipper Tom Abell (82) and their good work was backed up by youngsters Tom Banton and George Bartlett, who both hit half-centuries.
But Hampshire’s seamers stuck to their task and Abbott produced an inspired spell of four for 22 late in the day as seven wickets fell for just 55 runs in bright sunshine.
By the close, the visitors had replied with 15 for one from seven overs, losing Ollie Soames, who was caught behind off Jamie Overton for a duck.
Somerset won the toss and elected to bat first on a used pitch. Clearly expecting it to turn as the game progressed, the home side selected a second spinner in Dom Bess in place of seamer Jack Brooks.
Hampshire made an early breakthrough with the total on 18, Azhar Ali’s poor season continuing when he played all around a straight ball from Abbott and departed lbw for 12.
But Abell showed good judgement on when to leave the ball as he and Hildreth saw off the new ball and laid the foundation for the biggest stand of the day.
Hildreth looked in prime form from the start and went to fifty off 78 balls, with 7 fours. By lunch, he and Abell had taken the total of 98 for one.
Abell was content to play the supporting role as Hildreth continued to prosper after the interval, bringing up the 45th first-class century with a six over deep square off a long-hop from leg-spinner Mason Crane, who struggled for any semblance of control.
Abell went to a watchful half-century from 126 balls, with 5 fours, just the innings Somerset required to cure their top order batting problems.
With the score on 196, Hildreth was struck a blow on the helmet by Fidel Edwards, who worked up good pace from the River End. The next ball was also short and the batsman pulled to short mid-wicket where Keith Barker took a good diving catch.
Abell fell with the total on 237, edging Abbott to first slip and at tea it was 289 for three. Young guns Banton and Bartlett demonstrated their potential with a stand of 116 off 128 balls, both exuding confidence, before Banton – who had survived a stumping chance on 17 – fell lbw to James Fuller for 79.
Steve Davies departed cheaply to Fuller and the second new ball was taken at 379 for five. From then on Hampshire hit back strongly led by Abbott.
He removed Lewis Gregory (25), Jamie Overton and Tim Groenewald for ducks with successive balls, and last man Jack Leach for six.
Bartlett became a second victim for Edwards, having contributed an impressive 68 and Somerset had cause to feel disappointed with their late order collapse.
Hampshire had substitute fielder Aneurin Donald keeping wicket for much of the day after Tom Alsop suffered a hamstring injury during the morning session. Donald was later replaced by specialist keeper Lewis McManus, who had been summoned to the ground.
During the lunch interval Azhar Ali was presented with his Somerset county cap by Marcus Trescothick.