Hooker: Tom Youngs v Richard Hibbard
A contrast in styles. The bustling, whole-hearted Youngs, who starts against the Waratahs does not have the scrummaging solidity of Hibbard but his ability to cover the ground is valuable on harder surfaces. Another good 50 minutes on Saturday and his bulkier Welsh rival really will have to pull out all the stops.
Loosehead prop: Mako Vunipola v Alex Corbisiero
Horses for different courses. Vunipola is improving by the day and is capable of making major dents with ball in hand. But with Cian Healy and Gethin Jenkins both out of the tour, would the Lions be better starting games with a more experienced scrum operator in Corbisiero?
Blindside flanker: Tom Croft v Dan Lydiate
Everything boils down to balance. Croft's athleticism and lineout ability would, in theory, be a nice foil for Sam Warburton and Jamie Heaslip. But Lydiate's chop-tackling has been one the mainstays of Wales's success and Gatland will be reluctant to leave him out.
Openside flanker: Sam Warburton v Justin Tipuric
The captain needs a big game against the Waratahs. But Warburton has always wanted nothing to be guaranteed and it would be a huge call for Gatland to drop him for Brisbane. Tipuric has been excellent so far, as has Sean O'Brien, and the Osprey may yet feature in the Tests at some point.
Wing: Sean Maitland v Alex Cuthbert
If George North is unavailable – and he will need to train with the Test team early next week to be in with a chance of playing – the Lions will have a growing wing dilemma. Cuthbert and Maitland, as things stand, would appear to be vying for one spot. The Welshman is a more physical presence and a prolific try-scorer but Maitland has looked quicker over the ground on this tour and gets his chance in Sydney.
