Sussex held their nerve in cricket's equivalent of the penalty shoot-out last night to reach the quarter-finals of the Twenty20 Cup.

In farcical conditions at the Oval, James Kirtley bowled a superb final over in which he took three Surrey wickets to help guide the Sharks to a five-run win in a game reduced to five overs per side.

It did not look as if the crowd of 16,800 would see any action after persistent rain set in an hour before the scheduled 5.40pm start.

But the rain stopped, the Surrey groundstaff did a miraculous mopping-up operation and in gloom even the most enthusiastic village players would not have played in the game finally got underway at 7.40pm.

A frenetic hour later Sussex were celebrating thanks to a superior fielding display on a soaking outfield and crucial cameos from four of their players.

Chris Adams, who tops the batting averages in Twenty20 this season, peered through the gloom to hit 19 off eight balls.

But the explosive acceleration came from Chris Nash who smashed a six and three fours in a nine-ball 24.

Maybe it is his bat, which his sponsors say is the same they make for Kevin Pietersen. Whatever, Nash has suddenly become a vital Twenty20 performer for Sussex because of his ability to judge length quickly and get under the ball and find the boundary.

Even in his Horsham days Nash will not have batted in light as poor as last night's but it did not seem to faze him.

Openers Murray Goodwin and Luke Wright went cheaply, but he helped Adams plunder 16 from Rikki Clarke's over and, after Adams had top-edged to short fine-leg, he weighed into Jade Dernbach whose solitary over went for 20.

Crucially, Nash scored off every ball he faced while three wides, and the runs they scored off them, took Sussex to a total they must have fancied defending in conditions which were never going to get any easier.

Rana Naved was unfortunate to concede three boundaries in the first over as Surrey's big-hitters James Benning and Ali Brown looked to give their pursuit of 66 to win a turbo-charged start.

But Robin Martin-Jenkins dragged it back in his over when the dangerous Brown was run out by a combination of Hodd's reflexes and a brilliant throw from mid-wicket by Rana.

Then Mushtaq Ahmed struck twice in his over to put Sussex in control.

Benning's slog sweep picked out Rana on the square-leg boundary and Clarke was deceived by a quicker ball. It would have been an even better over had Azhar Mahmood not belted his Pakistan compatriot down the ground off the back foot for the first of three sixes.

The big-hitting Azhar was the key to Surrey's hopes now and, in the absence of Saqlain Mushtaq, Adams must have thrown Wright the ball with some trepidation.

The all-rounder has proved expensive in Twenty20 so far and did not even bowl in Tuesday's win over Essex.

And his skipper probably feared the worst when Mahmood swung Wright's first ball over extra cover for six. Ramprakash also cleared the rope off the fifth delivery and with those two together Surrey fancied their chances of scoring 17 off the last over to win.

But Sussex's catching was faultless and Nash held on at third man to remove Mahmood for 22 off the first ball Kirtley sent down.

Ramprakash swung the next delivery over square leg for six but, in trying to clear the rope at long on off the next delivery, he picked out Wright who held another fine catch under pressure.

Eleven off three balls was now too much to ask for Surrey, especially when Kirtley claimed a third wicket with his fifth ball when Butcher sliced a drive to backward point.

It was great entertainment for the crowd, who deserved to see some cricket after waiting for over two hours in the drizzle, but Butcher's reaction as he trudged off at the end suggested he felt otherwise.

Despite being without Matt Prior and Mike Yardy, two of their most important players in past Twenty20 campaigns, Sussex have reached the last eight for the first time.

But their chances of making it to finals day will improve still further if they can have home advantage in the last eight and that means another performance as committed as last night's against Hampshire at Hove tonight.