Sussex's hopes of any progress in the Twenty20 Cup are all but over after they discovered just how small the margins for error are in cricket's newest competition.

Surrey sentenced them to a second successive defeat in the south group while maintaining their own unbeaten record after they passed Sussex's 143-8 with 11 balls to spare in front of a 3,000 crowd at the Imber Court ground in Esher last night.

It was comfortable in the end for Surrey, who have won all three of their games so far, but the outcome might have been different had Robin Martin-Jenkins not stepped backwards over the rope as he 'caught' Ian Salisbury on the long off boundary.

Jonathan Batty had reverse-swept Mark Davis for four three balls earlier and the 18 Surrey scored off the 17th over gave their run chase just the impetus it needed.

Martin-Jenkins had his head bowed for the next few minutes and his mood hardly improved when he returned to the attack in the penultimate over and saw his first ball deposited over the mid-wicket boundary by Batty for six, the last shot in a stand of 32 from 21 deliveries.

Sussex had fought back well in defence of what always appeared to be an insufficient score on a club ground where the boundaries are only 60 metres and the outfield lightning-fast.

Mushtaq Ahmed and Davis applied such a stranglehold that Surrey's star-studded line-up failed to score a boundary between the ninth and the 15th overs. Mushtaq also ended a stand of 46 in four overs between Adam Hollioake and James Benning when he removed both batsmen in the space of three deliveries.

Sussex were favourites when Tim Ambrose stumped Mark Ramprakash and Graham Thorpe was run out by Matt Prior's direct hit from mid off in the 15th over, but that was as good as it got for the visitors.

Sussex's total always looked 15-20 runs light as they paid for their inability to build on an impressive start from Bas Zuiderent and Matt Prior who put on 42 in six overs after Chris Adams had won the toss.

The brakes were applied first by Salisbury, who had Prior and later Martin-Jenkins caught at long off, and then Phil Sampson who had Zuiderent caught behind for a run-a-ball 35 before tempting Murray Goodwin to loft his slower ball straight to long on.

Adams and Tim Ambrose gave the innings much needed momentum by adding 41 in four overs but Adams was caught behind immediately after hoisting Hollioake into the crowd at mid-wicket and the Surrey captain bowled Ambrose in the next over.

Instead of accelerating at the end, Sussex managed a modest 16 in the final four overs and Hollioake, thanks to clever changes of pace, finished with 4-31 after removing Kevin Innes and Mushtaq in the last over.

It looked like being a very early night when Alistair Brown and Ian Ward launched the reply with a barrage of blows which belatedly brought a remarkably subdued crowd to life.

But Paul Hutchison celebrated his competition debut with the important wicket of Brown while Martin-Jenkins induced Ward to hole out with his first delivery before his evening went rapidly downhill.

Surrey (2 pts) beat Sussex (0 pts) by 4 wickets