Derbyshire 194 for 5 (Madsen 100*) beat Durham 193 for 5 (Robinson 43, Jones 43, McKiernan 3-29) by five wickets
Madsen scored a brilliant unbeaten 100 off 47 balls with 11 fours and three sixes as the Falcons completed their highest T20 run chase by cruising to 194 for 5 to set them up for the quarter-finals.
Durham had posted a challenging 193 for 5 through Ollie Robinson’s 43 from 27 balls and Michael Jones’s 42 off 22 with Falcons leg-spinner Mattie McKiernan taking 3 for 29.
But Madsen was at his inventive best and supported by Shan Masood’s 31 off 28 balls and Hilton Cartwright, 38 from 23, the Falcons sealed a ninth group win with five balls to spare.
Durham had lost nine of their previous matches but started well after Jones smashed 19 from the first over by Ben Aitchison who was making his first Blast appearance of the season following a back injury.
The seamer was driven for three consecutive fours before Jones launched him over the long on boundary and with Scott Borthwick finding his range after an uncertain start, Durham were 67 without loss after the powerplay.
But McKiernan shifted the momentum by removing them both in consecutive overs as Borthwick failed to clear long on and Jones drove to long off.
Ashton Turner pulled the leg-spinner for six but fell next ball trying to repeat the shot and it was left to Robinson to pick up the tempo.
After he survived a sharp chance on 20 at backward point, Robinson pulled and drove Alex Hughes and Luis Reece for three sixes as 31 came from the 14th and 15th overs.
Robinson skied Aitchison to long off but Brydon Carse scored 17 from nine balls and Jonathan Bushnell an unbeaten 25 off 20 to take Durham to a competitive total.
The Falcons lost Reece in the first over, lbw playing across the line at Carse, but Masood was soon into his elegant stride, easing the ball to the ropes on both sides of the wicket.
Madsen scooped Ben Raine over the wicketkeeper for six in the fifth over and pulled Nathan Sowter for another before a savage straight drive almost took out Raine on its way to the fence.
The danger signs were flashing for Durham as Madsen tore into Carse, pulling him for four and driving him for a third six to reach 50 off only 25 balls.
Durham had to break the stand and Andrew Tye delivered by trapping Masood lbw in the 10th over which cost only three runs.
Raine struck in the 11th when Leus du Plooy cut to backward point but Cartwright marked his first Blast appearance for the Falcons by driving Borthwick and Sowter for sixes..
Cartwright pulled and cut Tye for two fours and Madsen inflicted further damage in the 16th when he pulled Borthwick for four before the bowler’s shy at the stumps fizzed away to the boundary.
Cartwright was caught at long off but Madsen cruised to his hundred to complete a memorable afternoon for him and the Falcons.