Northamptonshire 152 for 4 (Cobb 57, Rossington 50) beat Leicestershire 149 for 5 (Pettini 56, Gleeson 3-20) by six wickets
Chasing just 150 after Mark Pettini's 56 for the visitors, Cobb and Rossington knocked off the bulk of the chase with a partnership of 89 for the second wicket in 9.4 overs. Northants cruised home with three overs to spare and now, with 11 points on the board, just two more wins from their final seven matches should be enough for a quarter-final place - a home tie is very much in their sights.
Rossington arrived in superb touch after a career-best 138 not out in the County Championship during the week and here made his third T20 fifty and second for Northants in 29 balls with nine fours. His timing was exceptional with some clean striking down the ground and also showed a clever touch with two late cut fours - the second of which during a over from Jigar Naik that went for 12 to leave only 57 needed from the final 10 overs.
Cobb has relished the number three role and was again in excellent touch. He began by cutting Rob Taylor for his first boundary and he lifted another over midwicket. Kevin O'Brien was introduced and his first ball was heaved over mid-on. His third half-century in four inning was raised in 40 balls with four fours and a six. He chipped Cameron Delport to extra-cover for 57 when two were needed to win.
Northants didn't need a contribution from Richard Levi, in his first game back after a shoulder injury. He took 12 from the opening over - two leg side flicks and a straight drive - but edged Clint McKay to third man. His failure mattered not. There was time for Ben Duckett to lift Mark Cosgrove down the ground and wide of midwicket for boundaries as he and Cobb took their side home.
Leicestershire's total was well below par. Their 149 for 5 was built around a partnership of 74 in 8.1 overs for the third wicket between Pettini and O'Brien. They recovered the innings after the early loss of Mark Cosgrove for 2 and Cameron Delport for 6 - both bowled by Richard Gleeson, whose opening two overs conceded only seven runs.
But Pettini clipped the first ball of Azharullah's spell for six over midwicket - an over that yielded 17 runs and injected momentum into the innings. Petting swung Azharullah to long leg and deftly cut Steven Crook for four en route to a half-century in 31 balls with six fours and a six.
Cobb ended the stand with the second ball of his spell - O'Brien chipping him into the hands of Graeme White at long-on - and three overs later Pettini also fell, trying to paddle sweep White and being plumb lbw for 56. It left Leicestershire 111 for 4 with five overs remaining.
Paul Horton, playing his first T20 of the season, was left to try and provide the late-innings power and he twice classically drove through extra-cover for four. But facing the first ball of the final over, was struck in the ribs by a Gleeson beamer and retired hurt for 29. Only six runs came from the final over.