Marcus Trescothick scored his fourth century in eight first-class innings at Wantage Road as Somerset marginally had the better of it on day one against Northamptonshire.
The opener, who also made it four centuries for the season, reached the milestone in the final over before the tea interval as he battled through the morning session before flourishing after the break in making 124 out of a total of 366-8.
He was given excellent support by Peter Trego (77) who, after being given not out from his very first delivery as Andrew Hall claimed a low catch at first slip off David Willey, contributed heavily to a fifth-wicket partnership of 174.
There was one black mark on the day for the visitors, however, after Craig Kieswetter was forced to retire hurt with a laceration under his right eye and a suspected broken nose after being hit by a Willey bouncer.
That particular event was part of an incident-packed hour after the lunch break which saw James Hildreth trapped lbw by Willey, Kieswetter felled and Trego reprieved before it all settled down and those doing the batting began to dominate.
On a warm day that encouraged swing throughout and on a pitch that bounced enough to keep the bowlers interested, the first session was edged by the home side who made good inroads into the top order.
Chris Jones was the first to go when he loosely drove at Muhammad Azharullah and lost his off stump and there was a similar outcome when Willey cleaned up Nick Compton with a delivery that left him.
Colin Ingram, on his four-day debut for the club, then pulled Olly Stone to Matt Spriegel at square-leg and when the interval arrived the score was 93-3.
That had been advanced to 249-4 when tea arrived as once everything had calmed down, Trescothick and Trego, who made it to 50 shortly before his partner got to three figures, motored along at five-an-over.
The home side, who plugged away commendably all day, missed a gilt-edged chance to break the partnership when Kyle Coetzer put down Trego at second slip off Stone but they finally broke through just before when Trescothick, having struck 20 fours, edged Hall to slip.
The second new ball was taken immediately and it accounted for Trego, hit in front by Stone, in the very next over.
Craig Overton and Lewis Gregory did not hang around for too long but George Dockrell and Alfonso Thomas saw out the final half an hour without any further setbacks.