Gloucestershire 160 for 3 (Marshall 72, Cowan 70) beat Worcestershire 159 for 7 (Andrew 43) by seven wickets
Hamish Marshall led from the front as Gloucestershire boosted their hopes of a quarter-final place with a seven-wicket Friends Life t20 win over Midlands/Wales/West Division leaders Worcestershire.
The skipper hit a scintillating 72 off 49 balls, with six fours and a six, sharing a second-wicket stand of 142 in 15 overs with impressive debutant Ed Cowan - Australia's Test opening batsman - as the hosts chased down a target of 160 for victory with 12 balls to spare.
Worcestershire had posted 159 for 6 after winning the toss, Gareth Andrew top-scoring with 43 and captain Daryl Mitchell hitting 31 off just 13 balls. Spinners Ed Young and Muttiah Muralitharan stood out for Gloucestershire, conceding only 43 from their combined eight overs.
It looked likely to be a testing target on a slow pitch. But after losing Benny Howell in the opening over for a first-ball duck, the home side quickly took control, Marshall reaching a 35-ball half-century, having been badly dropped on 14 by James Cameron at deep square off David Lucas.
Australia A captain Cowan emerged from a sketchy start to also strike the ball handsomely, making his runs off 48 balls, with nine fours and two sixes. By the time Marshall was out only 17 runs were needed. The result put Gloucestershire on nine points, just one behind Worcestershire, Somerset and Warwickshire with each team having two games left to play.
Worcestershire suffered a major blow when Moeen Ali was bowled by the second ball of the match from Ian Saxelby, having hit the first through the covers for four. The visitors struggled to gain any momentum as Phil Hughes drove a catch to mid-on off Liam Norwell and Vikram Solanki was taken at extra cover off Young.
Cameron did his best to stabilise the innings with 32 off 32 balls before being caught at third man by Cowan, Gloucestershire's new temporary overseas signing, off James Fuller.
It was Mitchell who provided the necessary acceleration, hitting six fours, and taking the pressure off Andrew, who blossomed himself to strike two sixes and four other boundaries. After Young and Murali had bowled so economically the last four overs went for 55 as seamers Norwell, Fuller and Saxelby lacked control under the onslaught from Mitchell and Andrew.