Paul Horton held the Lancashire batting together with his first LV County Championship century of the season on the opening day against Somerset at Taunton.

The opener made a career-best 155 not out in a total of 297 for five after his side had been invited to bat first under cloudless skies. Kyle Hogg contributed an unbeaten 69, helping to dig the visitors out of trouble at 153 for five.

The unbroken partnership of 144 changed the complexion of the day after Ben Phillips (three for 43) and Charl Willoughby (two for 88) had put Somerset on top.

The hosts were without skipper Justin Langer because of a shoulder injury sustained while fielding in the Pro40 match against Essex the previous evening. Marcus Trescothick took over, as he is expected to do for next season, and duly won the toss.

Opening bowlers Willoughby and Alfonso Thomas did not enjoy much luck early on as former Somerset player Luke Sutton and Horton built an opening stand of 58.

It was broken after Sutton needed treatment for a blow on the head from a short ball from Phillips. The next delivery saw him edge a leg-side catch to wicketkeeper Craig Kieswetter and depart for 26.

It was 89 for one at lunch with Horton one short of his half-century. He reached fifty straight after the interval off 92 balls, with seven fours.

But Somerset hit back strongly in the afternoon session. Willoughby started the fightback by pinning Mal Loye lbw for 14 with the total on 99.

VVS Laxman was caught behind for 12 chasing a wide ball from the same bowler and it was 128 for four when Mark Chilton fell for a duck, also caught by Kieswetter off Phillips.

Francois du Plessis did not last long either, driving at a wide one from Phillips and giving the wicketkeeper his fourth catch, having made only a single. Lancashire were 153 for five in the 50th over and in disarray.

But Horton was still there and reached a gritty hundred with a pulled four off David Stiff. It was his 18th boundary and he had faced 155 balls.

Somerset could have dismissed him on 121, but Kieswetter spilled a diving chance off Zander de Bruyn. By then Hogg was well set and the tall left-hander moved confidently to fifty off 85 deliveries, with five fours.

There was no stopping Horton, who reached 150 off 239 balls, having extended his boundary count to 25. His 26th brought up his career-best score, beating the 152 he had made twice, against Hampshire in 2007 and Yorkshire in 2008.

(reopens) Langer's replacement in Somerset's team was Taunton-born Jos Buttler, making his first-class debut the day after his 19th birthday.

It has been a big week for the young batsman, who on Monday was named in Somerset's final squad of 15 for the Twenty20 Champions League tournament in India next month.