Northamptonshire 249 for 6 (Willey 91, Duckett 61) beat Somerset 247 for 8 (Hildreth 55, Cooper 48, White 4-37) by four wickets
David Willey's powerful run-a-ball 91 led Northamptonshire to a comfortable four-wicket win over Somerset at Wantage Road and kept their quest for a Royal London Cup quarter-final on track.
After the great escape against Worcestershire a day before, Northamptonshire won in far more comfortable circumstances thanks to Willey's fine innings.
His stand of 95 with Ben Duckett broke the back of a chase of 248 and despite a late-innings wobble, the victory was very straightforward.
Willey was promoted to open the batting after a poor run of form but began circumspectly before getting into the groove - hitting five sixes in a thoroughly entertaining knock.
Willey brought up his half-century in 52 balls. Another sweep just evaded mid-on running back as the part-time off-spin of Tom Cooper was introduced - but next ball he swung his fifth six into the Lynn Wilson centre.
He said afterwards: "I like batting at the top of the innings and I've been in a bit of bad nick at the minute. I picked up a couple of things from the stats and made a couple of changes before the game and I got into better positions today.
"I wanted to give myself a bit of time with it being quite a poor wicket and me being in not great touch and I knew if I batted through with the target only five an over we should win the game.''
An imperious lofted straight drive over mid-off against Jim Allenby was perhaps the best stroke of his innings but he fell nine short of a third List A century when he was sharply caught and bowled by Max Waller.
Duckett's own half-century, made in 59 balls, was the perfect compliment to Willey's power with two reverse sweeps and a sumptuous cover drive off Waller the pick of his strokes.
He fell trying to drive a Peter Trego slower ball and was caught at extra-cover and two further wickets went down as Northamptonshire only won with an over to spare despite their cruise past 200.
But it was still an easy victory and Graeme White's second-best figures in List A cricket led another strong Northamptonshire's fielding performance.
The assistance available was evident immediately as he turned his second ball past the outside edge of Trego and into his off stump before changing ends to have Tom Abell caught behind for 35.
White also lured Allenby into sweeping a chance to Josh Cobb at deep midwicket - Cobb throwing the ball back into play falling over the rope before receiving to complete the catch - and clean bowled Craig Overton to finish with 4 for 37.
Spin did half of the bowling in the Somerset innings. Like White, Rob Keogh bowled his full allocation and made an important breakthrough, bowling Cooper for his first List A wicket. It ended a stand of 64 between Cooper and James Hildreth for the fourth wicket.
Hildreth, following his rescue act for Somerset on Sunday against Gloucestershire, again made a half-century to steer his side's innings having won the toss.
He swept White for four to bring the hundred up in the 23rd over and went past fifty in 57 ball with four boundaries. However, trying to cut Cobb - the third spinner used by Alex Wakely - edged behind for 55.
Overton soon followed for just three and at 194 for 7, Somerset were in danger of falling well short of a competitive score.
However, Alex Barrow - who has endured a difficult season and was dropped from the Championship side - made a valuable 31 in 33 balls in his second game back in the first XI.
He and Groenewald, who struck Cobb into the car park during his 24 in 20 balls, added 52 for the eighth wicket to get Somerset up to 247 - but it proved at least 20 runs too few.