Harry Wilson and Tim Ryan remain chances to face the Crusaders in the Queensland Reds' Super Rugby Pacific quarter-final in Christchurch.
But Harry McLaughlin-Phillips is all but certain to be ruled out of Friday's clash after a head knock suffered late in the side's big defeat of Fijian Drua added to the side's injury-riddled season.
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Incumbent Wallabies captain Wilson failed to finish in Saturday's 52-7 win at Suncorp Stadium after suffering a knock to the same arm he fractured earlier this season.
Wilson had scans on Sunday but was spotted at Ballymore on Monday and is yet to be ruled out of the sudden-death clash.
Winger Ryan (ankle) can also prove his fitness this week but the six-day turnaround will likely rule out back-up playmaker McLaughlin-Phillips.
Liam Wright, Matt Faessler, Lukhan Salakaia-Loto, Massimo De Lutiis and Alex Hodgman are among the key Reds on their swollen injury list.
Enigmatic utility forward Seru Uru (knee) could return for the clash.
The Reds, who ended a 25-year winning drought in Christchurch last season, will fly to New Zealand on Wednesday.
With McLaughlin-Phillips sidelined it's likely Lynagh will need to clock on for an 80-minute shift.
The Wallabies hopeful, in silky form against the Drua, is confident the side can hold their nerve and upset the Crusaders.
"We're just going to play how we want to play and won't let the occasion dictate that," the No.10 said.
The Reds were well beaten in Christchurch earlier this season and blown away in last year's quarter-final loss to the Chiefs in Hamilton.
"Just play smart footy ... when things don't go our way, get little wins and try to stack them rather than have those errors back to back," Lynagh said of how they'll attempt to control the contest in enemy territory.
"We've got belief to turn it around if things aren't going our way.
"We've come a long way and added some good additions."
Former Reds playmaker James O'Connor has excelled as a replacement No.10 after shifting to the Crusaders this year.
The Wallabies veteran is back in the conversation for Test honours ahead of the British and Irish Lions series after wearing the No.10 against the tourists 12 years ago.
"I haven't heard from him in a couple of weeks, but it'll be good to come up against him again," Lynagh, who counted O'Connor as a mentor when he arrived at Ballymore, said.
The son of Wallabies great Michael is bidding to make history, with no Australian father-son combination yet to run out against the British and Irish Lions.
"I want to take care of the Reds' season first," Lynagh said of his aspirations.
"The deeper you go, the better opportunity and more time to show what you've got, but I want to take care of what's in front of us at the moment."
