Notts Outlaws captain hails spinner Calvin Harrison
Harrison took 4 for 36 as the North Group winners claimed a ninth victory after bowling out Durham for 143.
It sets up the defending champions up nicely the home quarter-final with Hampshire on 25th August. with the skipper believing his side should be full of confidence going into the tie.
Mullaney said: "I felt it was really important for us to send the crowd away with a proper performance.
"I think we are showing we are a really versatile team and can perform on any type of surface. I'm really pleased for Calvin (Harrison), his bowling has gone from strength to strength and I think he's only going to get better.
“It was a great performance. We got off to a great start in the power play with Ben Duckett and Alex Hales.
The outfield was rapid and the boundaries were short.
“The bowling performance was great. We kept simple plans and got off to a great start in the power play.
“We are in a great position and should be very confident going into the quarter final.
“The team has changed over the last three years, but we have found a formula each time at the end of the group stage.
“We played really well, but there is still room for improvement. It is massive being at home in the quarter-finals.
“Our aim was to get out of the group stages and get a home tie, but we know it is only job half done.”
The game was marred by a nasty injury to Brydon Carse.
The pace bowler was hit in the face by an Alex Hales drive when he slipped in his follow-through in the 4th over and played no further part in the match.
Ben Duckett, with an unbeaten 74 from 41 balls and 43 not out off 17 balls by Steven Mullaney propelled the Outlaws to 221 for 4.
Durham collapsed to 59 for 6 and were bowled out for 143 in 16 overs.
Joe Clarke and Hales gave the Outlaws early momentum before both fell as the Outlaws ended the powerplay on 70 for 2.
Although Tom Moores was lbw first ball to Scott Borthwick, Duckett and Samit Patel got the Outlaws back on track by adding 67 in 7 overs.
Duckett swept Liam Trevaskis for two fours and a six and made Durham pay for dropping him on 28.
Matty Potts held a much harder catch running in from long on to remove Patel for 34 off 26 balls but that only opened the way for Mullaney’s brutal late onslaught.
He pulled Graham Clark’s leg spin for three sixes in the 15th over which cost 24 and he and Duckett plundered 83 from 37 balls to take the Outlaws to an imposing total.
Any chance Durham had of chasing it down vanished when they lost four wickets in the powerplay.
David Bedingham struck some defiant blows before he skied Dane Paterson and after Cameron Bancroft was yorked by Zak Chappell, Harrison removed Ben Raine and Borthwick in the 9th over.
Potts at least went down swinging, heaving Patel for three sixes in the 13th over, but Harrison wrapped up a comprehensive win.