Pakistan on Sunday sealed their highest successful chase and clinched the tri-series played at Zimbabwe's Harare Sports Club by chasing down Australia's 184-run target up to the last over.

This is Pakistan's ninth successive T20 series win and has helped the team retain their top position in the T20 ranking.

It is also Pakistan's first series win against Australia in the past 28 years, the last time Pakistan won Austral-Asia Cup played in Sharjah in 1990.

Youngster Asif Ali hit the winning four that brought glory to the green shirts, Shoaib Malik accompanied him on the pitch.

Opener Fakhar Zaman cracked a career-best 91 to help set up Pakistan's six-wicket win.

Zaman shared in a century stand with Shoaib Malik as Pakistan recovered from an early wobble in their pursuit of Australia's 183 for 8, and Malik then showed all the experience of an 18-year international career to see his team home with an unbeaten 43.

It looked as though Australia had produced a masterstroke in opening the bowling with Glenn Maxwell's offspin as debutant Sahibzada Farhan was stumped off the first ball he faced and Hussain Talat sliced a catch to point three balls later to derail Pakistan's chase.

Australia threatened to storm to victory, but Zaman quickly set about re-building the innings. First, he added 45 with captain Sarfraz Ahmed to take his team out of immediate danger, and he then added 107 for the fourth wicket with Malik to seize the advantage for Pakistan.

When Zaman fell cutting out to deep cover, Pakistan still needed 30 from 24, but while Malik remained at the crease their chase was always safe.

Their ultimate victory capped a mixed day for Pakistan.

Australia captain Aaron Finch was given a first-ball reprieve when he was dropped by Malik in the deep after top-edging a hook, and several misfields allowed any pressure with the new ball to be immediately dissipated.

Their errors allowed Australia to get off to a flier, with Finch putting together a 95-run opening stand with D'Arcy Short. Short was also dropped just after he had reached a 39-ball fifty, but he could not better his previous T20I high score of 76 and Pakistan's bowling at the death kept Australia in check.

From 95 for 0 after the first 10 overs, Australia lost 8 for 88 and their 183 for 8 was not quite enough to better Pakistan in the final analysis.