Ravi Bopara celebrated news of his England recall with a century but it was not enough to prevent Essex Eagles falling to a six-wicket loss against Somerset Sabres in the Friends Provident t20.
The victory moves Somerset level on points with Sussex at the top of the South Group and guarantees them a place in the quarter-finals with three games still to play.
Bopara, who will link up with the England squad for Monday's NatWest Series decider against Bangladesh as a replacement for the injured Ian Bell, hit 105 not out in Essex's total of 173-6.
Opening the innings, the right-hander took advantage of the short boundaries at Chelmsford to slam eight fours and six sixes during his 62-ball innings.
He was, however, given little support with Alastair Cook (20) and Mark Pettini (21) the only other to even reach double figures.
And the Sabres, led by 78 from free-scoring opener Marcus Trescothick, chased down their target from the first ball of the final over.
Trescothick also took a liking to the intimate confines of the playing area to dispatch nine fours and a six from 51 balls.
James Hildreth chipped in with 43 from 35 deliveries during a second-wicket stand of 101 from 67 balls.
Both fell with the winning line in sight but fifth-wicket pair Zander de Bruyn and Jos Buttler completed the win without undue alarm.
Despite the defeat, Essex stay in third in the South Group on 16 points and, with three games left, remain in control of their own destiny.