Khawaja keeps England at bay after Broad strikes in Ashes opener
Australia were struggling at 67-3 after Stuart Broad struck twice in two balls to remove David Warner and Marnus Labuschagne before England captain Ben Stokes captured the prize wicket of star batsman Steve Smith.
But at tea on the second day they were 188-4, with opener Khawaja 84 not out.
That still left Australia 205 runs behind England's first-innings 393-8 declared featuring Joe Root's 118 not out -- the former captain's first Ashes hundred in eight years.
Australia looked as if they might get through the second session without losing a wicket as Khawaja and Travis Head shared a partnership of 81.
Both left-handers went after Moeen Ali, each hitting the recalled off-spinner for sixes in the all-rounder's return of 1-82 in 18 overs on his Birmingham home ground.
But Stokes, unlike many a previous England skipper confronted by a spinner conceding runs, kept Moeen, in for the injured Jack Leach, going in what was the bowler's first Test in nearly two years since he 'retired' from all red-ball cricket.
The skipper's faith was rewarded when Head, fresh from a hundred in Australia's World Test Championship final win over India at The Oval last week, fell for a typically brisk 50 off 63 balls when he dragged a drive off Moeen to Zak Crawley at midwicket.
Australia's 148-4 should have become 148-5 when Cameron Green, on a second-ball nought, charged at a sharply-turning Moeen delivery only for wicketkeeper Jonny Bairstow, who made a run-a-ball 78 on Friday, to miss a clear stumping opportunity after snatching at the chance.
Broad had earlier reduced Australia to 29-2 in the seventh over of Saturday's play.
During the drawn 2019 Ashes in England, left-handed opener Warner had averaged a meagre 9.50 in 10 innings and was dismissed seven times by the veteran seamer.
And the 36-year-old seamer yet again proved to be Warner's nemesis.
Warner had fought hard for a score of nine on an overcast morning favouring England's quicks when he chased a wide ball from Broad and inside edged into his stumps.
The roars that greeted Warner's exit became deafening next ball when Labuschagne, the world's top-ranked Test batsman, fell for a golden duck.
He edged a sharp Broad outswinger that was brilliantly caught one-handed by Bairstow, diving low to his right in front of Root at first slip.
Smith survived the hat-trick delivery but rarely looked comfortable in a 59-ball stay that didn't feature a single boundary.
Stokes's bowling fitness had been called into question by a longstanding left knee injury, but the lively all-rounder struck when he rapped Smith on the back foot with a nip-back ball.
The batsman's review served only to uphold South African umpire Marais Erasmus's decision and Smith, whose twin centuries in the Ashes opener at Edgbaston four years ago powered Australia to a 251-run win, was out for 16.
