Skipper Babar Azam hopes Pakistan's batters can keep faith in their abilities as they attempt to create history by chasing the highest-ever target in Test cricket to beat Australia in Karachi.

Babar cracked a fighting century with great support from opener Abdullah Shafique on Tuesday as Pakistan thwarted Australia's hopes of a quick win in the second Test in Karachi.

Set a daunting 506-run target, Babar knocked his sixth Test century — and second against Australia — to guide Pakistan to 192-2 and raise hopes of an improbable victory, or even a fighting draw.

At the close, Babar was unbeaten on 102 and Abdullah 71 as the pair added 171 for the third wicket, leaving the home team needing another 314 runs in the 90 overs of the final day for a win, or bat out three sessions for the draw.

“The match hasn't finished yet,” Babar told the broadcasters. “We need to continue batting like this and keep the belief (to create history).

“Definitely, my hundred was needed by the team and my plan was to build a partnership, which Abdullah and I did, but we need to continue like this (on Wednesday).”

Pakistan lost Imamul Haq (one) and Azhar Ali (six) before Abdullah and Babar led the fightback, leaving Australia wicketless in the last session — despite taking the second new ball after 80 overs.

Babar top-edged a sweep off spinner Mitchell Swepson towards short fine-leg for two to reach the three-figure mark, his first in 21 innings since his 143 against Bangladesh in Rawalpindi in February 2020.

His hundred came in 247 minutes with 12 boundaries.

Abdullah was as solid as his skipper, having so far hit four boundaries and a six as he and Babar batted defiantly for 265 minutes.

No team has ever chased more than the 418-7 the West Indies amassed against Australia at Antigua in 2003, while Pakistan's highest successful chase was 377 against Sri Lanka at Pallekele in 2015.

Australia, resuming their second innings at 81-1, batted for just 26 minutes at the start of play to add 16 runs before declaring on 97-2.

The visitors scored 556-9 declared in their first innings then dismissed Pakistan for 148.

The home team had hoped Azhar would anchor the second innings but the senior batsman was trapped lbw by Cameron Green while trying to evade a short-pitched delivery.

Azhar chose not to review as he trudged off but was left to regret it as television replays showed he had gloved the ball.

At 21-2, Australia seemed to have the upper edge and were looking to take a 1-0 lead in the three-match series but their efforts were thwarted by a slow turning pitch and the brilliance of Pakistan's batting pair.

Australia could have had Abdullah on 20 but the experienced Steve Smith spilled a straightforward catch in the slips off pacer Pat Cummins.

Australia's batting coach Michael Di Venuto described the chance as part of the game.

“Smith has good hands and he takes nine out of ten such catches but that happens,” said Di Venuto.

“It's going to be hard work (tomorrow) and since there is variable bounce on the pitch, it's going to be interesting.”

Despite cracks on the National Cricket Stadium pitch, Australian spinners Nathan Lyon and Swepson failed to get a vicious turn.

Earlier, Imam and Abdullah were all caution as it took them until the fifth over to score the first run before Lyon struck.

The in-form Imam, who scored a hundred in each innings of the drawn first Test in Rawalpindi, was trapped lbw for one as he failed to connect with a sliding delivery.

Earlier, Marnus Labuschagne was bowled off a sharp Shaheen Shah Afridi delivery for 44 to prompt skipper Cummins to call Australia's innings to a close with first-innings century-maker Usman Khawaja, who was born in Pakistan, remaining 44 not out.

Australia are on their first tour of Pakistan since 1998, having previously refused to tour the country because of security fears.