Australia in box seat after Pakistan wilt in Karachi

Australia declared their first innings on 556 for nine and then skittled out Pakistan for 148 to seize control of the second test in Karachi on Monday.

After more than two days of leather-hunt under a harsh sun at the National Stadium, Pakistan's abject batting capitulation handed Australia a mammoth first innings lead of 408.

The hosts were spared the ignominy of a follow-on but Australia's overall lead bulged to 489 as the touring side finished day three on 81-1.

Their Islamabad-born opener Usman Khawaja was batting on 35 with Marnus Labuschagne on 37.

"We knew the pitch would deteriorate to some degree, not sure we thought that would happen so quickly," Australia fast bowler Mitchell Starc said.

"Both teams have been able to achieve that reverse swing and I think the way our batters played themselves first two days, full credit to them for setting up a massive total."

Earlier, Australia milked 51 runs in nine overs before declaring their innings immediately after crossing the 550-mark.

Skipper Pat Cummins smashed three sixes in his unbeaten 34 off 36 balls against a jaded Pakistan attack on a slow track.

Pakistan were let down by their openers who showed poor judgment to depart either side of the lunch break.

Abdullah Shafique made 13 before running himself out and opening partner Imam-ul-Haq, who smashed twin hundreds in the drawn series opener in Rawalpindi, fell to Nathan Lyon in a sudden rush of needless aggression.

Starc then claimed two in two to rock Pakistan.

The left-arm quick lured Azhar Ali (14) into driving a full and wide delivery and Cameron Green grabbed the edge at second slip.

Starc followed that with a searing yorker to trap Fawad Alam lbw for a duck.

Mohammad Rizwan somehow denied Starc a hat-trick but looked pretty much a sitting duck during his 13-ball stay.

Dropped in the slip by Steve Smith off Cummins, Rizwan got another life in the very next ball when an lbw decision against him was overturned.

It did not really matter though as Cummins returned to dismiss Rizwan caught behind in his next over.

Starc owed his third wicket to Alex Carey who was convinced he had taken a catch from Sajid Khan even though the bowler himself was not sure and the umpire did not think so either.

Carey convinced Cummins to review the original not-out decision and Sajid had to go after replays confirmed an edge.

Babar top-scored for Pakistan with 36 before becoming debutant leg-spinner Mitchell Swepson's (2-32) first test victim.

"Our batting was not what it should have been on such a flat track," lamented Pakistan fast bowler Hasan Ali.

"They have to take more responsibility in our second innings. The ball is reversing but if we can negotiate those phases, there are plenty of runs to be scored on this pitch."