Any lingering doubts over Usman Khawaja as Australia's Test No.3 for the Ashes have been dismissed after the Queensland captain's lone hand in the top of the table Sheffield Shield clash with NSW in Brisbane on Monday.

Khawaja's unbeaten 78 was the shining light for the myFootDr Queensland Bulls side that was bowled out for 183 by a NSW attack minus rested Test stars Mitchell Starc, Josh Hazlewood and Pat Cummins.

Stumps were called with NSW 3-83 in reply after Blues captain Steve Smith was caught at bat-pad by Sam Truloff for 44 off Jack Wildermuth (2-13) with five balls left for the day.

Khawaja looks primed for the first Test starting at the Gabba on November 23 after moving his Shield tally to 295 runs at 98.33.

But Khawaja's journey in and out of the Test side since his baggy green debut six years ago has taught the elegant left-hander to keep his bold statements on the field.

"I am feeling good, things are going well but I know how quickly it can change," Khawaja said.

"You can't think too far ahead but my mindset doesn't change, I want to keep scoring runs."

Only five Queenslanders reached double figures against a new look Blues attack of Trent Copeland (3-33), Doug Bollinger (3-38) and Sean Abbott (1-42).

NSW's Test offspinner Nathan Lyon warmed up for the Ashes opener with 3-59.

Test opener Matt Renshaw was unluckily given caught behind off Copeland in just the 12th over.

He was clearly unhappy with the decision, standing his ground before trudging off.

Khawaja felt for Renshaw after the opener became one of Test 'keeping aspirant Peter Nevill's four dismissals.

"I thought he missed it but that's cricket," he said.

Khawaja looked untroubled after arriving at the crease in the fifth over with the Bulls 1-11 when Joe Burns fell for two.

His 192-ball innings lasted more than four hours and featured eight fours and a six.