Lucas, 20, had shown promise at five-eighth in two Super Rugby pre-season wins and a close round-one loss to the Brumbies.
But he will be used as a finisher against the big-bodied Lions, with O’Connor shifting from inside centre and utility back Hamish Stewart recalled at No.12 for Sunday morning’s clash (12:05am).
Wallabies lock Izack Rodda will also earn his first start of the season after an off-season slowed by minor ankle surgery, while Alex Mafi will begin at hooker with Brandon Paenga-Amosa (ankle) out for up to eight weeks.
It will be O’Connor’s second start at No.10 for Queensland after calling the shots in his 2015 Reds debut and an ideal platform to push his case for a Wallabies berth in a position that remains up for grabs under new national coach Dave Rennie.
O’Connor played at No.12 in Friday’s loss in Canberra but finished at No.10 as the Reds coughed up a 10-point halftime lead to lose 27-24.
Thorn indicated O’Connor and Lucas might be in and out of the No.10 jersey at different stages of the season in a horses-for-courses approach.
“We just want to have a look at him (O’Connor) and we also think Isaac can really bring something in that last 30, 20 minutes as well,” the coach said.
“We’re pleased with both James and Isaac; they’re just playing different roles this week and I’d say you’ll see some stuff this season, sometimes playing different spots there.
“We’re looking forward to James having a shot there and working with Hamish and also what Isaac can bring (off the bench).”
In a brutal three-week road trip to start the season, the Queensland outfit will move on to Argentina the following weekend to play the Jaguares, who thumped the Lions last weekend at home.
“Around the world trip; no other sport really does it, let alone a contact sport,” Thorn said.
“So, if you can get a victory on this trip, you can call that a success.”
Queensland: Bryce Hegarty, Jock Campbell, Jordan Petaia, Hamish Stewart, Henry Speight, James O’Connor, Tate McDermott, Harry Wilson, Liam Wright, Angus Scott-Young, Lukhan Salakaia-Loto, Izack Rodda, Taniela Tupou, Alex Mafi, JP Smith. Res: Sean Farrell, Dane Zander, Josh Nasser, Angus Blyth, Seru Uru, Moses Sorovi, Isaac Lucas, Hunter Paisami.
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