Powered by a brilliant 152 from England's one-day wicketkeeper Craig Kieswetter, Somerset thrust themselves into the title reckoning and checked Warwickshire's ambitions with a dramatic victory at Taunton, taking 21 points to go third in the First Division table.
Somerset, chasing 271 to win after bowling Warwickshire out for 124 in their second innings, overcame a terrible start, in which they lost both openers in the first eight balls, thanks to Kieswetter and Nick Compton, who put on 166 for the fourth wicket.
At that point, Somerset looked to be cruising to victory, with only 90 more needed with 27 overs remaining.
Kieswetter's progress never faltered. He passed 100 off 123 balls with 10 fours and four sixes – all off Jeetan Patel – to which he added three more, another off the spinner, one off Chris Wright and one off Keith Barker.
But Barker then threatened to deny them by taking five wickets for 19 runs in the space of 26 balls – Kieswetter among them – before Peter Trego and Gemaal Hussain guided Somerset nervously home.
Sussex climbed to fourth place after holding on to beat Durham by two wickets in a similarly anxious finish at Arundel, where the seamer Steve Magoffin took 6 for 22 before scoring 23 not out to help Sussex scramble past a modest target of 94 to win.