South African Jacques du Toit hit a six and four off the last two balls as Leicestershire beat Durham by seven wickets at the Riverside.
Kyle Coetzer (39no) and Gareth Breese (37) helped Durham to 144-8, with teenage paceman Alex Wyatt taking 3-14 on his Twenty20 debut for the Foxes.
Aussie James Allenby (53) and skipper Paul Nixon (53no) then put on 82 for the third wicket.
But it was du Toit who came in to help Nixon take the Foxes home on 144-3.
Leicestershire's first win of the competition, at the third attempt, takes them level on two points with Durham and Yorkshire in the North Division.