Former South Africa batsman JP Duminy has hammered five sixes in seven balls as leg-spinner Eddie Leie conceded 37 runs in a single over, the second-most in the history of List A cricket.

The 37 runs in the over, which came via five sixes, a no-ball that went for four and a two, is second only to the 39 runs Bangladeshi bowler Alauddin Babu conceded in a one-day match in a match in Dhaka in 2013. On that occasion, Babu's over went 5nb-wd-6-4-6-4-6-wd-6 as Zimbabwean Elton Chigumbura went on the attack.

Playing for the Cape Cobras at Newlands and with 32 runs needed for victory, Duminy hit four consecutive sixes at the start of Leie's seventh over and briefly had the rare feat of six consecutive sixes in his sights.

QUICK SINGLE Rampaging Ross sets new single over high

But the spinner conceded just two runs from his fifth delivery, a flatter delivery that the left-hander hit into the deep for two. However, after what should have been the final ball of the over was hit for four and called a no-ball, Duminy hit the seventh delivery over the rope to secure the 37-run over and victory for his side.

The analysis for the over read 6-6-6-6-2-5nb-6.

"It is not every day you get the opportunity, so of course I was trying to go for the six sixes in an over," Duminy, who finished unbeaten on 70 off just 37 balls, said.

"I initially thought it was all about the bonus point. I looked up at the scoreboard and we needed 35 with four overs still to go to get the bonus point, so I just decided to take Eddie on.

"I was striking the ball really cleanly, and when the first two went for six, I figured I might as well give it a full go now because regardless whether I get out we would still have secured the bonus point. It was enjoyable."

Duminy's effort eclipsed the South African record of 36 runs in an over, a mark set by Herschelle Gibbs when he hit six sixes off an over in a 2007 World Cup match against the Netherlands.

Leie finished with figures of 1-90 from seven overs, the worst in Knights history, eclipsing the 0-88 conceded by a young Kagiso Rabada in the summer of 2014-15.

Duminy's feat came just three months after South Australia's Alex Ross hit 32 runs off one Nathan Lyon over, which broke the Australian List A record.

Ross the Boss takes 32 off Lyon's over

Playing in a JLT One-Day Cup match at Hurstville Oval, Ross went 4-6-6-4-6-6 as the Redbacks won by 45 runs.

"Basically once the wind picked up a bit in that over ... I tried to get him the over before but he bowled really well," Ross said.

"I got back in the box and tried to hit him as deep as I could.

"It came off today but next week it might not."