The Lions go into Saturday's potentially decisive Test against Australia by making five changes - two enforced - from the team who won the series opener 23-21 in Brisbane.
With Paul O'Connell and Alex Corbisiero injured, England's pair of Geoff Parling and Mako Vunipola will make their first test starts for the Lions while Alex Cuthbert, Mike Phillips and Tom Croft have been replaced by Tommy Bowe, Ben Youngs and Dan Lydiate.
Bowe's return from a broken right hand is predictable but Youngs is more of a surprise. He joins brother Tom, the hooker, in the starting line- up. The Wallabies have made two changes with Kurtley Beale in at full back for Berrick Barnes and Joe Tomane taking over from Digby Ioane on the wing.
Captain Sam Warburton is urging his players to finish the Wallabies off here in Melbourne to avoid a repeat of the 2001 Lions tour when a 1-0 lead was squandered and the home side took the series 2-1 - winning the decider in Sydney.
Warburton said:" This is the biggest game my career because the potential achievement is something no Lions team has managed for four tours. You are normally nervous in the build up to a big game but this is all about excitement and it can't come quick enough. We are going to need to do something special because Australia were only a kick away from winning last weekend. If we were 1-0, we would believe it could be turned around.
"They are going to come out firing and they are not down and out.
" I have had nervous excitement since arriving here in Melbourne and waking knowing that in five days you could be test series winners and now it's two days to go. The game can't come quickly enough and all the talk around the squad has been about finishing it off this Saturday.
"There isn't any complacency because the momentum will change completely if we have to go to the third test inn Sydney because that would mean the Wallabies coming off a win. We are motivated to finish it off."
Gatland believes the changes he has made will add a greater physical threat and allow his forwards to deal with a ferocious assault from the Wallabies who will hope the absence of O'Connell affects the Lions pack.
Gatland said:" Tommy is a quality player and the experience he brings is very important and you have to give credit to the surgeon because others were saying it would take six to eight weeks to heal. He is a fantastic player who had made a fantastic recovery from injury. Mike Phillips was available but his knee has been sore and the decision was to rest him for this week and he is potentially important for the third test. We felt it was prudent to have him 100 per cent ready for next week.
"This is a do- or- die match for Australia and we have add a bit more physicality to our side up front with Dan Lydiate coming into the back row. One or two changes were forced on us because of the injuries to Paul O'Connell and Alex Corbisiero but the other show the strength in depth we have in this squad .
"It's never about not changing a winning team - it's about picking the best side to do a job for us. Our whole focus is on winning the match and the series and the last thing we want to do is be 1-1 going into Sydney. We have spoken to Craig Joubert, the referee, and got some clarity on the break down and our discipline has to be better."
Teams for Australia versus British and Irish Lions, second Test, Etihad Stadium, Melbourne, Saturday, 1100 BST.
Australia: K Beale (Melbourne Rebels); I Folau (New South Wales Waratahs), A Ashley-Cooper (New South Wales Waratahs), C Leali'ifano (Brumbies), J Tomane (Brumbies); J O'Connor (Melbourne Rebels), W Genia (Queensland Reds); B Robinson (New South Wales Waratahs), S Moore (Brumbies), B Alexander (Brumbies), K Douglas (New South Wales Waratahs), J Horwill (Queensland Reds, capt), B Mowen (Brumbies), M Hooper (Brumbies), W Palu (New South Wales Waratahs).
Replacements: S Fainga'a (Queensland Reds), J Slipper (Queensland Reds), S Kepu (New South Wales Waratahs), R Simmons (Queensland Reds), L Gill (Queensland Reds), N Phipps (Melbourne Rebels), R Horne (New South Wales Waratahs), J Mogg (Brumbies).
British and Irish Lions: L Halfpenny (Wales); T Bowe (Ireland), B O'Driscoll (Ireland), J Davies (Wales), G North (Wales); J Sexton (Ireland), B Youngs (England); M Vunipola (England), T Youngs (England), A Jones (Wales), A-W Jones (Wales), G Parling (England), D Lydiate (Wales), S Warburton (Wales, capt), J Heaslip (Ireland).
Replacements: R Hibbard (Wales), R Grant (Scotland), D Cole (England), T Croft (England), S O'Brien (Ireland), C Murray (Ireland), O Farrell (England), A Cuthbert (Wales).
Referee: Craig Joubert (South Africa).
Assistant referees: Chris Pollock (New Zealand) and Romain Poite (France).