Prop Taniela Tupou, nicknamed ‘Tongan Thor’ because of his size, power and heritage, may help fill the Valetini void.
Capped 58 times by Australia, Tupou started for Joe Schmidt’s side in November against England and Ireland, but has struggled for form since.
He starts at tight-head in the place of injured Allan Alaalatoa for what will be his first appearance of the Test series.
“The conversation that came out after the first Test was that he doesn’t fit Schmidt’s model of playing, which is extremely detailed,” Barclay said.
“He is an X-factor player with big moments in games but probably doesn’t have the quality of input throughout a game.”
In an attempt to prove his form to Schmidt, Tupou played for New South Wales Waratahs and First Nations & Pasifika in earlier tour games.
“He is fuelled by anger at not being involved until the last game,” Monye added.
“The series is not on the line so you might just be unleashing a beast.
“If he can lock down a scrum and then release havoc, you’ll get a good version of him.”
Despite last week’s improved display by the Wallabies, Barclay believes Andy Farrell’s side will easily become the first Lions team since 1927 in Argentina to record a series whitewash.
“That is where I think Australian rugby has been for 18 months to two years. Potential for great performances but don’t get it done, or they can’t do it consistently,” he added.
“The Lions will look at that game and forget the first half happened in Melbourne. They will think ‘we are winning 3-0’. I think they will win well.”
