Johan van der Wath's short stint as Sussex's overseas player ends next week but he will leave the county with happy memories after guiding the Sharks to a sensational win yesterday.

Sussex looked to be dead and buried at 216-8 in the 37th over after Ian Blackwell's career-best 134 not out off 71 balls had helped Somerset pile up 297-6.

But van der Wath had other ideas, smashing 73 off just 43 balls with three sixes and five fours. Sussex needed 41 off the last four overs but such was van der Wath's placement and power that he struck the winning runs off Gareth Andrew with two balls to spare. How Somerset will rue the fact that they dropped him twice.

After Ian Ward and Mike Yardy had gone cheaply, Matt Prior and skipper Chris Adams kept Sussex ahead of the required rate in a stand of 71 in 11 overs for the third wicket.

Prior hit ten fours and three sixes in his third totesport half-century of the season. But after hitting 77 off 56 balls he was run out by James Hildreth's direct hit from extra cover as he answered Adams' call for a tight single.

Adams and Murray Goodwin kept Sussex ticking over but their challenge appeared to have ended when Keith Parsons took four wickets in five overs with his skiddy medium pace, including Adams for 59.

But no one reckoned on van der Wath's act of cricketing violence. Together with Jason Lewry, who did an important job in making sure his partner had as much of the strike as possible, they added a match-winning 82 in eight overs of mayhem before a disbelieving Taunton crowd of 3,500.

It certainly overshadowed an awesome display of hitting by Blackwell which brought the Somerset all-rounder 100 of his runs in boundaries.

Blackwell and Rob Turner put on a county record 151 off just 81 balls for the sixth wicket, of which Turner contributed an unbeaten 47. Blackwell had strode to the crease in the 23rd over with his side struggling on 88-5.

He smashed ten sixes - the most by an opposition batsman against Sussex in the one-day league - and ten fours.

Seven of Blackwell's sixes came off the hapless Mushtaq Ahmed including four in one over as the leg-spinner was tortured on his return to his former county. His 1-76 was the second worst bowling analysis in league history by a Sussex bowler.

While Mushtaq was punished for bowling too short, James Kirtley got similar treatment even though he tried to pitch the ball up as Blackwell blasted 25 came off his penultimate over.

Nearly all of his sixes sent the crowd sunbathing on the mid-wicket boundary scattering for cover and all were struck with impeccable timing rather than brute force. The umpires had to call for six replacement balls.

Until Blackwell came in Sussex had been in control. Kirtley and van der Wath both took a wicket with the new ball and Lewry, making his first totesport League appearance for nearly a year because Luke Wright has a side strain, removed Matthew Wood and Aaron Laramann with successive deliveries.

But at the end, even Blackwell was forced to acknowledge a sensational cameo from van der Wath.