Matt Critchley hit a cavalier 86, but Derbyshire lost to Leicestershire by six wickets at The 3aaa County Ground.
The 21-year-old played fluently for his highest score of the first-class season, but wickets continued to fall at regular intervals on Day Three and with no other batsman able to score above 30, Derbyshire were all out for 184.
Set 133 runs to win, Leicestershire rarely looked troubled, and despite consolation wickets for Duanne Olivier (2-37) and Hardus Viljoen (2-48), the visitors claimed a six-wicket win in the final session.
Billy Godleman was out to the third ball of the day, Mohammad Abbas (6-54) picking up his third of the innings with an in-swinging delivery which set the tone for a good spell of bowling from the Pakistan international.
Alex Hughes doubled his overnight score, but a partnership of 42 with Critchley was the highest stand Derbyshire could register and Hughes became Abbas’ fourth wicket, caught behind for 30.
Daryn Smit fell with the score 128-6, but Critchley pressed on, keen to score quickly with the tail and he reached his third half-century of the campaign off 71 balls, including seven fours.
Hardus Viljoen (0) and Duanne Olivier (9) were out quickly, while Tony Palladino offered some resistance, eventually out for eight off 32 deliveries.
Determined to attack the Leicestershire bowlers before the innings was out, Critchley hit Ben Raine for four then six, before he was out to Abbas on 86, the seamer picking up his sixth wicket.
Chasing 133 to win with 53 overs left in the day, Leicestershire lost a quick wicket as Viljoen got the necessary early breakthrough, Sam Evans well caught by Harvey Hosein for two to leave the visitors 3-1.
Paul Horton (48) and Ackermann (58) looked good at the crease and quickly built a 97-run partnership to take Leicestershire to the brink of victory.
Both were out to the South Africa pace duo, but proved to be consolation wickets and Lewis Hill (3 not out) hit the winning runs to give Leicestershire a six-wicket win.
Vitality Blast is back! Derbyshire Falcons host seven Twenty20 games this July and August. Purchase your tickets in advance and save from £4. Buy online or call 01332 388 101.