Lancashire 191 for 5 (Horton 63, Brown 52, Croft 50) beat Leicestershire 151 for 8 (Clark 3-41) by 40 runs
Half-centuries from Karl Brown, Paul Horton and Steven Croft enabled fast-improving Lancashire to set Leicestershire a target that proved far beyond them on a good pitch at Grace Road.
Croft followed up his innings with a fine bowling spell, with his four overs going for just 17 runs and including that rare event in T20 cricket: a wicket maiden.
Leicestershire captain Mark Cosgrove put the visitors in after winning the toss, but although Ashwell Prince went early, bowled off the inside edge by Ben Raine, Brown and Horton ensured the power play was a productive one, with Brown particularly effective, hitting six fours and two sixes in going to his 50 off just 31 balls in the ninth over.
His dismissal was a curious one, run out after backing up too far and failing to regain his ground when Cosgrove back-handed the ball into the stumps, but Horton was joined by Croft in keeping the run rate high. Horton's 50 came off 38 balls, including seven fours, and in the same over in which he holed out to long-on off Clint McKay, Croft went to his own half-century, from just 25 balls.
Leicestershire lost wickets regularly in their reply after Jordan Clark persuaded Cosgrove to hit a length delivery into the hands of Horton at extra cover, and though debutant Aadil Ali hit two sixes in his lively 26, they fell well behind the run rate after Croft, bowling the 12th over, did not concede a run and saw Elliott loft a leg stump full toss to Liam Livingstone on deep backward square.
With James Faulkner almost as economical, the win was assured, keeping Lancashire in the frame to qualify for the quarter-finals, and Leicestershire, after three consecutive defeats, needing to win their final two games to have any chance of doing the same.