Ben Green claimed four wickets as holders Somerset leapfrogged Sussex Sharks into second place in the Vitality Blast South Group with a six-wicket victory at the Cooper Associates County Ground, Taunton.
The visitors could post only 158-9 after losing the toss. Harrison Ward top-scored with a rapid 39 and medium-pacer Green finished with four for 17 from three overs.
In reply, Somerset made 162-4 with 2.2 overs to spare. George Thomas hit 42, including seven fours, Tom Abell was 47 not out and Sean Dickson made 28. Tymal Mills was the most successful Sharks bowler with two for 28.
The result made sure of a place in the last eight for Somerset – and made them favourites to secure a home quarter-final tie with one group game left to play.
The batting highlights of the Sharks’ six-over powerplay were Daniel Hughes’s three successive fours in the third over, bowled by Craig Overton, and the first six of the match struck by Ward off Jake Ball in the fifth over.
Hughes had fallen earlier in that over, miscuing a pull shot to mid-on and at the end of the powerplay Sussex were 49-1.
That became 66-1 when Ward greeted the introduction of Jack Leach with a four and six off his first two deliveries.
But the England left-arm spinner quickly struck back by having the opener caught sweeping after facing 23 balls – and that was as good as it got for the visitors as Somerset turned the screw in the middle overs.
Green struck twice in his first over, removing Tom Clark and John Simpson to catches in the deep, including a diving effort from George Thomas.
At the halfway point in their innings the Sharks were struggling on 71-4.
Tom Alsop was dropped by Thomas off the first ball of the 13th over, sent down by Green, but perished to the next delivery as Overton pouched a comfortable catch at mid-on off a full toss.
James Coles, who hit a brisk 26, and Nathan McAndrew (20) paid the penalty for testing Dickson’s arm from the boundary edge and were both run out attempting to turn one run into two.
Green then claimed his fourth wicket when the same fielder held a simple catch off McAndrew.
The Sussex total never looked likely to be enough. And so it proved as Tom Banton and Thomas got Somerset off to a flyer.
They shared a stand of 34 in four overs which ended when Banton clipped a catch to deep square off Mills’s first ball of the game.
At the end of the powerplay the hosts were 56-1, with Thomas and Tom Kohler-Cadmore going well.
They took the score to 70 in the eighth over when Thomas was caught at long-on off Danny Lamb, having faced 30 balls and enhanced his growing reputation as replacement for the injured Will Smeed.
Abell survived a caught and bowled chance to Mills but the pace bowler struck later in the 10th over as Kohler-Cadmore, on 20, lofted a catch to deep cover.
It mattered little as Abell and Dickson both cleared the ropes and Dickson ended any doubt about the result with three successive boundaries off McAndrew at the start of the 13th over.
With 10 runs needed, Dickson was run out by Clark’s direct hit from the boundary, having done his job.