Lancashire 164 for 2 (Hameed 65, Jennings 63) beat Northamptonshire 269 (Holder 72, Keogh 66, Vasconcelos 50, Mahmood 6-37) by 45 runs (DLS method)
England Lions seamer Saqib Mahmood became only the fourth Lancashire player to take six wickets in a List A innings and the first in 21 years as he set up a commanding Royal London Cup win over Northamptonshire at Emirates Old Trafford.
Mahmood, 22, returned a career best 6 for 37 as the Steelbacks, invited to bat, were bowled out for 269 in 50 overs.
He then watched openers Haseeb Hameed and Keaton Jennings hit 65 and 63 respectively on the way to 164 for 2 in the 29th over when rain arrived, with Lancashire winning by 45 runs on Duckworth Lewis Stern. The Red Rose have now won two and lost two in the North Group.
Colin Croft, David Hughes and current coach Glen Chapple (twice) have all taken six-fors for Lancashire, the last being Chapple at Yorkshire in 1998.
Mahmood struck three times with the new ball to leave the score at 26 for 3, so a 270 target was a triumph for a Northants side who have now won one, lost three. They were boosted by half-centuries for Ricardo Vasconcelos, Rob Keogh and West Indies captain Jason Holder, who received treatment to his lower left leg early in his innings and later did not take the field.
Keogh's unusual 66 off 97 balls did not include a four or six, while Holder hit seven fours and two sixes in 72 off 58 as he looked in no obvious discomfort. They shared 89 inside 16 overs for the sixth wicket to recover from 103 for 5 in the 26th before former Red Rose allrounder Luke Procter gave the visitors further impetus with a late 36.
Mahmood gave Lancashire the ideal start by bowling Josh Cobb. He then had Richard Levi caught at deep square-leg and Alex Wakely brilliantly caught behind one-handed by Dane Vilas.
Vasconcelos and Keogh steadied with a 76-run fourth-wicket stand before Keogh and Holder united to back up fifties in Sunday's home win over Warwickshire.
Holder hit sixes over midwicket either side of reaching 50 off 47 balls before falling to Mahmood trying to repeat the dose in the 45th over. The catch was an outstanding relay effort on the midwicket boundary between Australian Glenn Maxwell and Rob Jones, the latter diving to complete the catch at the second attempt.
Maxwell then took two catches at the death, including Ben Sanderson running in from deep cover to hand Mahmood his sixth.
The early stages of Mahmood's career have been beset by injuries, with his previous best of 5 for 60 coming in last year's North v South series in Barbados.
In reply, Jennings and Hameed shared a measured opening stand of 130 inside 24 overs, only for the former to be run out by a direct hit from Saif Zaib at square leg.
Jennings reached a run-a-ball fifty and Hameed's came off 60 balls before Maxwell hit successive leg-side sixes off Zaib's left-arm spin to move into double figures.
Hameed was caught behind off Procter's seamers, with Lancashire 154 for 2 in the 29th over, before Vilas hit two boundaries in 10 off three balls immediately prior to the rain arriving. Maxwell was unbeaten on 20.