Graham Napier produced an amazing performance - smashing an unbeaten 152 - as Essex reached 242 for three to beat Sussex by 128 runs in the Twenty20 Cup.

It was not the Chelmsford floodlights that lit up the ground but the breathtaking display by the 28-year-old.

He set a new domestic record individual score for Twenty20 cricket with arguably the most spectacular demonstration of big-hitting at the County Ground, with deliveries repeatedly struck cleanly with superb timing that had the crowd roaring their approval as the home side reached their highest-ever total in the competition.

"It was a fantastic feeling," said Napier.

"I was seeing the ball well from the moment I went in. I middled one or two and then got into a rhythm and went on from there."

His 152 beat the previous-best Twenty20 figure of 141 not out set by Cameron White for Somerset in 2006, when playing against Worcestershire, and included an incredible 16 sixes.

That feat equals Andrew Symonds' world record, although the Australian achieved his in first-class cricket when playing for Gloucestershire against Glamorgan in 1995.

Napier also struck ten other boundaries, having faced only 58 deliveries, and none of the six bowlers used by Sussex escaped his breathtaking heroics.

Both Dwayne Smith and Chris Liddle conceded three successive sixes while Kirtley went for four sixes in five balls in the final over of the innings that produced 29 runs.

James Kirtley conceded 67 from his four overs - a record in domestic Twenty20 cricket - and Michael Yardy 52 from four overs.

Jason Gallian joined Napier in an early run-fest as 77 were gathered from nine overs, after Mark Pettini had been dismissed for four, but when Gallian left, having scored 26, the fireworks really started as James Foster arrived at the crease.

He and Napier put on a storming 119 in seven overs, with Foster making 48 from 23 balls, as the overall innings produced 190 runs in boundaries and Sussex chased a forlorn hope.

Totally dejected, the visitors failed to spark and, when Maurice Chambers struck twice in one over to send both Smith and Matt Prior back to the pavilion, Sussex were 66 for four and their position became worse when James Middlebrook prised out both Yardy and Chris Adams four overs later with the total having advanced to 94 and six.

The innings folded quickly with Danish Kaneria collecting the last two victims as Sussex were bowled out for 114, leaving Essex to celebrate the biggest margin of victory ever by runs in the domestic competition.