Pakistan captain Babar Azam has long established his credentials in limited-overs cricket, but his 196 against Australia put him up there with some greats in the long form of the game too.

Azam fought valiantly for 10 hours and seven minutes in an innings lasting 425 deliveries to help Pakistan salvage a draw on Wednesday in the second Test in Karachi.

His heroic innings became the second-longest knock in the fourth innings of a Test, just 36 minutes behind Michael Atherton's 185 not out that ensured England saved the 1995 Johannesburg Test against South Africa.

Azam added 228 for the third wicket with Abdullah Shafique (96) and 115 for the fifth with Mohammad Rizwan (104 not out) as Pakistan defied the Australian attack for 171.4 overs.

The epic draw kept the three-match series -- Australia's first in Pakistan for 24 years -- tied at 0-0 after the first Test also ended in a draw in Rawalpindi.

Former Pakistan captain Misbah-ul-Haq told AFP that Azam's performance was "career defining".

The 27-year-old Azam's remarkable effort was the highest score by a captain in the fourth innings of a Test, surpassing Atherton's South Africa knock and propelling him above the likes of Don Bradman and Ricky Ponting.

Azam also became the highest individual scorer for Pakistan in the fourth innings of a Test, surpassing Younis Khan's 171 not out against Sri Lanka in 2015.

His masterclass kept the Aussies at bay after the visitors dominated for five days and looked certain to win the match, having set the hosts a mammoth 506-run target.

"In terms of the context of the game, with the team under pressure, him being captain and as batter who had not scored a hundred for some time, this is his best innings," Misbah said.

"Such a match-saving innings gives you belief. I think this will go a long way in establishing his Test credentials," added Misbah, under whose captaincy Azam played his first Test in 2016.

   **- Fab five? -**
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Azam has a long-held ambition of becoming the best in the game.

From a ball boy at Gaddafi Stadium in Lahore in the 2007 Test between Pakistan and South Africa,

Azam graduated to play in the 2010 Junior World Cup and then skippered his country at the same tournament two years later -- scoring the most runs on both occasions.

He learnt the art of occupying the crease with a memorable 266 for State Bank against Habib Bank in the domestic Quaid Trophy Silver league in 2014, heralding his arrival.

Five months later he made his one-day international debut -- and did not look back.

But he was slow off the mark in Test cricket, his first century not coming until the 32nd innings.

"I was never in doubt about his talent because he has a solid technique," said Misbah. "He started to blossom in the West Indies (2017) and Australia (2019)."

Azam hit 104 and 97 on the Australia tour, suggesting he could rank alongside Australia's Steve Smith, India's Virat Kohli, New Zealand's Kane Williamson and England's Joe Root -- the so-called "Fab Four".

Azam is ranked number one batsman in the International Cricket Council's ODI and T20I rankings, but eighth in Tests.

With his Karachi effort, there could be a "Fab Five" in the not-too-distant future.