Nottinghamshire 318 (Mullaney 70, Taylor 58, Nash 52, Parkinson 5-68) beat Lancashire 309 for 9 (Jennings 136) by nine runs
Nottinghamshire, the Royal London Cup holders, reaffirmed their credentials with a thrilling come from behind win over Lancashire at Emirates Old Trafford during the opening night of the competition.
The Outlaws defended a target of 319 as the Red Rose county slipped from 245 for 3 after 40 overs when it looked like they would secure their record chase.
Lancashire's Keaton Jennings opened with an excellent 136 during a mixed day for him, with them finishing on 309 for 9, losing by nine runs.
He also claimed a career best two-wicket haul, but the England hopeful will be frustrated that, despite a third successive century in all forms, he fell in the 47th over to leave the score at 288 for 6. Harry Gurney had him caught at square-leg pulling before Jake Ball struck twice in the next. Left-arm seamer Gurney finished with three for 61.
After electing to bat, Outlaws captain Steven Mullaney crunched a whirlwind 70 during the final 20 overs of an innings which started well, stuttered and was revived fiercely on a superb surface.
Chris Nash and New Zealand overseas Ross Taylor hit 52 and 58, with the 84 for the fifth wicket in 12.2 overs shared between Taylor and Mullaney sparking a late flood of runs after 128 for one had become 164 for four inside 32 overs.
While the last 10 overs yielded 106 runs, Lancashire leg-spinner Matt Parkinson claimed all of his five wickets inside the last seven on the way to career best figures of five for 68 on his Red Rose List A debut. He had Taylor caught at long-off and Mullaney, who faced 54 balls, caught at cover.
Captain Liam Livingstone and Dane Vilas then attacked for 33 and 41 respectively, taking all the pressure off left-handed Jennings in the chase.
He shared half-century stands with both of them (70 with Livingstone and 63 with Vilas) as the hosts reached the 30-over mark ideally played at 179 for three. The former Durham man reached his fourth career List A off 98 balls with nine fours just under six overs later, becoming the fourth player to score a century on Lancashire List A debut.
Jennings added 87 for the fourth wicket with Steven Croft before the score fell to 245 for 4 in the 41st with the departure of the latter to Samit Patel.
At that stage, Notts were still behind, but they weren't for long as new ball pair Gurney and Ball combined to leave the target at 16 off the last, bowled by Ball, with only last pair Arron Lilley and Parkinson to get them.