Will Smith became Durham's first LV= County Championship centurion of the season as the visitors enjoyed a productive start to the match with Somerset at Taunton.
The opener made exactly 100 in a total of 353 for eight, Michael Di Venuto contributing 96 to an opening stand of 158, while Ben Stokes hit an attractive 60 off 79 balls.
Somerset stuck to their task in energy-sapping heat after losing the toss and fought back hard in the final session from a tea score of 264 for two. Peter Trego and Jamie Overton claimed two wickets each..
With Vernon Philander having been recalled by South Africa, the home side's pace attack lacked a cutting edge and they looked likely to be up against it on a good batting pitch under cloudless skies.
Smith and Di Venuto set the tone. On 38, Di Venuto was dropped by Trego in the slips off Alfonso Thomas, back in Somerset's team after playing in the Indian Premier League.
But it was a rare moment of alarm for the openers as they took the score to 128 off 32 overs by lunch, Di Venuto outscoring his partner to be unbeaten on 81 at the interval.
The left-hander looked on course for a certain century when edging an attempted cut shot off Thomas through to wicketkeeper Craig Kieswetter. He had faced 119 balls and hit 18 fours and a six.
Smith made only 46 before lunch and continued on his steady way to reach a chanceless hundred shortly before tea. It came off 192 deliveries and included 12 fours and two sixes.
The only wicket to fall during the afternoon session was that of Mark Stoneman (27), who called for a quick single to cover and failed to beat Jos Buttler's throw to Kieswetter after being sent back.
But after tea Somerset rallied. Smith miscued an attempted pull off Jamie Overton and fell to a tumbling catch by Thomas at mid-on.
Paul Collingwood's poor season continued when he drove a catch to cover off left-arm spinner George Dockrell, having made 12, and Ian Blackwell could score only seven against his old club before pulling a catch to square-leg off Overton.
When the aggressive Stokes was run out by Craig Overton, fielding smartly off his own bowling Durham were 326 for six and in danger of failing to cash in fully on their fine start.
Somerset took the new ball at 342 for six and eight runs later Phil Mustard joined the list of careless dismissals, pulling a catch to square leg off Trego. In the same over Callum Thorp edged to Alex Barrow in the slips and departed for a duck.
