Khawaja and Harris are under the most pressure to make way for Steve Smith.
A run out appeared the most likely mode of dismissal for the Australian openers, who, as expected, proved a class above a struggling second division attack.
Khawaja had the occasional dicey moment but was confident enough to advance down the wicket to Derbyshire’s seamers, a tactic he is unlikely to try against Jofra Archer, Stuart Broad and co.
The stand-in captain for this game, Khawaja reached his 50 in the second hour of the session, his first half-century since Australia’s last tour game, against Worcestershire.
Chasing 172, Australia reached 1/169 at lunch on the second day with Khawaja unbeaten on 68 and Mitchell Marsh on 24.
Marsh is considered next to zero chance of being recalled next week so it was curious he batted in front of Smith, who was subbed out of the second Test due to concussion and missed the game at Headingley.