Sussex’s hopes of making the quarter-finals of the NatWest T20 Blast suffered a setback as they went down to an 11-run defeat to Gloucestershire at Arundel Castle.

Hamish Marshall hit a 55-ball 90 in a stand of 120 for the second wicket with Ian Cockbain as Gloucestershire set an imposing target of 184-4 Ajmal Shahzad took career-best figures of 3- 26 to restrict the visitors but Sussex’s hopes of victory faded when skipper Luke Wright fell for 71.

Matt Machan blasted an 18-ball 31 to give the 6,000-plus crowd something to cheer as the Sharks finished on 173-9, Matt Taylor taking 3- 29.

The result lifts Gloucestershire to second in the South Group while Sussex remain fourth.

Gloucestershire got off to a slow start after being put in to bat and losing influential skipper Michael Klinger in the second over when the Australian was trapped lbw by Shahzad for two.

The visitors were 28-1 after the opening five overs but then Marshall and Cockbain began to up the tempo.

The pair put on 120 in 75 balls with Marshall bringing up his 50 from 31 balls with six fours and a big six off leg-spinner Will Beer over midwicket.

Cockbain made 37 from 33 balls – including sixes off Danny Briggs and Twenty20 debutant George Garton - before being caught off a leading edge to give Briggs a solitary wicket.

Marshall followed for an excellent 90 when he cut Shahzad straight to Matt Machan at point but the Gloucestershire innings did not lose any momentum after his departure.

Benny Howell blasted three sixes in a ten-ball 23 – including two off new England call-up Tymal Mills - before becoming Shahzad’s third victim in the final over as Gloucestershire set a testing target of 184-4.

Sussex made a positive start to the chase but lost opener Chris Nash for 13 when he top-edged an attempted sweep off Graeme van Buuren for 13.

The Sharks were 50-1 after the powerplay but suffered another blow when youngster Phil Salt was trapped lbw for 12 attempting to reverse-sweep Tom Smith.

Smith also hit New Zealand international Ross Taylor in front for 16 which increased the responsibility on Wright’s shoulders.

The Sussex skipper responded by bringing up his 50 from 38 balls and then launched Howell and Kieran Noema-Barnett for enormous sixes down the ground.

The game swung significantly back in Gloucestershire’s favour when Wright perished going for another maximum as he picked out the fielder on the midwicket boundary off Howell.

That left Sussex requiring 62 from the last five overs with two new men at the crease and it proved too tall a task despite Machan offering brief hope with three towering sixes.