Left-arm spinner Ashton Agar took a hat-trick as Australia crushed South Africa by 107 runs in the first T20I at the Wanderers Stadium on Friday.

Steve Smith, back in South Africa for the first time since the 2018 ball-tampering scandal, hit a top score of 45 for Australia, who made 196 for six after being sent in.

South Africa made a bad start against the pace of Mitchell Starc and Pat Cummins before Agar’s triple strike sent them hurtling to their all-time lowest T20 total of 89.

It was also the host country’s biggest defeat in the format.

Man of the match Agar finished with career-best figures of five for 24.

“It was really exciting, a highlight of my cricketing life,” he said.

But he gave praise to the fast bowling attack of Mitchell Starc, Kane Richardson and Pat Cummins who started South Africa’s collapse.

South Africa were reeling at 40 for four when Agar came on to bowl.

He had Faf du Plessis caught at deep cover with his fourth delivery, trapped Andile Phehlukwayo leg before next ball and Dale Steyn superbly caught at slip by captain Aaron Finch to complete the hat-trick.

Earlier, Smith and Finch (42) set up Australia’s big total with an aggressive second wicket stand of 80 off 52 balls, benefitting from some loose South African bowling.

The win extended Australia’s unbeaten run in the format to nine matches, with eight wins and one no-result. Their last defeat was in November 2018.

The second match of the series is at Port Elizabeth today with the third and final game in Cape Town on Wednesday.