Glamorgan 104 for 6 beat Middlesex 102 by four wickets
Glamorgan spinner Dean Cosker and Robert Croft took three wickets apiece as Middlesex slumped to 102 all out, their lowest score in Twenty20 cricket, and their fourth defeat in five matches in the Friends Life t20 South Division.
Glamorgan also struggled with the bat on a slow, turning, club pitch at Richmond but Alviro Petersen, their captain, held them together with 39 and Mark Wallace hit an unbeaten 40 to see them home by six wickets with 17 balls to spare.
Middlesex chose to bat first and Paul Stirling hit the third ball of the match over long off for six but wickets fell regularly after that with only Chris Rogers making any impression with 30 off 21 balls, including four fours.
The first two wickets fell to the seamers, Will Owen having Stirling caught at midwicket and Graham Wagg claiming Steve Crook caught behind before Cosker and Croft took complete control with their flight and guile.
Cosker took two wickets in three balls in his first over, Rogers clipping to midwicket and Neil Dexter being bowled round his legs.
Croft conceded 10 runs in his first over but he struck in his next when Scott Newman was bowled making room to cut.
Croft then had John Simpson caught at midwicket and Jamie Dalrymple, playing against the side he captained last year, stumped and Cosker had Tom Smith held at cover off a leading edge.
Spin claimed the last two wickets as well. Wagg, who had reverted to slow left-arm, bowling Ryan McLaren and Petersen having Tim Murtagh stumped off his offspin.
Glamorgan made a poor start when Mark Cosgrove played on to the first ball of the innings from Crook and they were running into trouble at 30 for 3 when McLaren had Jim Allenby caught at mid-on and Ben Wright leg before off successive balls.
Petersen had made his 39 off 32 balls, however, when he was bowled slogging at Dexter and Wallace kept his nerve to win the match with his 40 off 41 balls.