Somerset 209 for 5 (Trescothick 87*) beat Nottinghamshire 206 for 9 (Wessels 53, Rehman 6-16) by five wickets
Scorecard Abdur Rehman marked his Clydesdale Bank 40 debut with 6 for 16 - a Somerset record in 40-over cricket - to help them to a five-wicket win over Nottinghamshire at Taunton.
The Pakistan left-arm spinner extracted turn and bounce from the pitch as Nottinghamshire struggled to 206 for 9, having been 96 for 1 in the 14th over. Riki Wessels hit 53, Michael Lumb 41 and Graeme White 39 not out.
Somerset needed only 29.2 overs to reach their target, Craig Kieswetter leading the way with a rapid 44 and skipper Marcus Trescothick seeing his side home with a responsible 87 not out off 69 balls with 10 fours and a six.
Rehman, who was given the new ball, switched ends twice during three spells and made the ball turn with increasing venom. His first victim was Alex Hales, lbw reverse sweeping for 7 with the total on 19.
There was no sign of the carnage ahead as Wessels and Lumb put on 77 for the second wicket in good time before Lumb carelessly pulled a to midwicket off Gemaal Hussain. Having switched to the River End, Rehman bowled Wessels middle stump with a ripper that pitched on leg and then had Adam Voges caught at slip by Trescothick for 1.
Hussain produced a beauty to clean bowl Chris Read for 10 and it was 133 for 5 in the 25th over. Samit Patel was then caught behind for 22 advancing to drive the left-arm spin of Arul Suppiah.
Rehman reverted to the Old Pavilion End to take three more wickets. Steve Mullaney was caught behind and Jake Ball taken at slip by Trescothick, both victims of turn, before Luke Fletcher drove to Steve Kirby at mid-off.
That meant the new overseas signing had bettered the previous best 40-over bowling spell by a Somerset player, set by Sir Viv Richards when he took 6 for 24 against Lancashire at Old Trafford in 1983.
The home side's reply was given a whirlwind start by Kieswetter, who smashed four fours and a six off the first five balls of the third over, sent down by Patel.
When England's one-day wicketkeeper departed for 44, Peter Trego smacked 26 off 20 balls to keep the momentum going and all the while Trescothick was building towards his first meaningful score since returning after ankle surgery.
He reached his half-century off 30 balls, with seven fours and a six. James Hildreth failed, offering a catch to slip to give White a second wicket on what was proving a good day to bowl left-arm spin, but Jos Buttler contributed 26 to put Somerset on the verge of victory.