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Much has been made of the coaches decision to only bring two recognised fly-halves on tour. At the time, they made reference to Stuart Hogg's ability to cover the position.
Few saw that as a realistic option, but Hogg will find himself at 10 for the first time since he was a schoolboy.
It's a bold move, because a poor performance could kill the young man's confidence, and the Lions have no viable substitute on the bench.
In a certain win, there is little chance a bad game would result in defeat, so the Lions are obviously taking the opportunity to rest Owen Farrell and Jonny Sexton.
Sean O'Brien and Justin Tipuric
The battle for the back row is getting hotter with each passing week. Sam Warburton returned to action over the weekend with a solid, if unspectacular, performance.
Tuesday, two of his main rivals for the role will line up on opposite flanks. The fact that Sean O'Brien now finds himself at six shows the coaches are still debating their best team.
If O'Brien continues in his rich vein of form, he could find himself in the test team on the blindside with Warburton or Justin Tipuric on the openside.
Or Tipuric may turn in another star turn and push Warburton onto the blindside. This battle could go any number of ways.
One gets the feeling that the coaches are giving Richie Gray every possible chance to play his way into form, and thus into the test side.
He offers a unique blend of size and athleticism that is unmatched in the squad but is being comprehensively outplayed by a number of his rivals.
A big performance in the loose Tuesday could push him back into contention, but another quiet game will see his chances fade.
Alongside him, Ian Evans is facing a similar make-or-break outing, but he doesn't offer anywhere near the quality of Gray at his best.
Weeks ago he was preparing to face the Pumas in Argentina, now he finds himself one big performance away from the matchday squad for the first test.
The injuries to Gethin Jenkins and Cian Healy have left Mako Vunipola as the sole loosehead prop left from the original squad.
With Vunipola seemingly have done enough to deserve his place in the test team, there is a spot on the bench which will come down to Alex Corbisiero and his fellow new arrival Ryan Grant.
Corbisiero is given the opportunity to start and will be hoping to showcase his destructive scrummaging.