Tommy Bowe and Ben Youngs have been handed starting spots by Lions coach Warren Gatland for the second Test against Australia on Saturday.
Ireland wing Bowe comes in for first Test try scorer Alex Cuthbert, while Youngs is preferred to Mike Phillips at scrum-half.
Elsewhere, injuries to Alex Corbisiero and Paul O'Connell mean that Gatland has drafted in Mako Vunipola and Geoff Parling.
The extra physical advantage offered by Dan Lydiate means the Wales flanker is promoted ahead of Sean O'Brien to replace Tom Croft on the blindside. O'Brien is on the bench, as is Croft.
Bowe's call-up caps a sensational return to fitness for the winger, after he suffered a broken hand just two weeks ago. George North, the scorer of a magnificent try in the first Test, retains his place on the opposite wing.
Bowe featured in all three Test matches in South Africa four years ago, and will bring added experience to the side. His return will see him wear a hurling glove on his injured hand to offer greater protection during the match, after he had three screws inserted to hold the fracture together.
Gatland said: "This is a do-or-die match for Australia. It's going to be a real battle out there and we have decided to add a bit more physicality to our side up front, and Dan [Lydiate] brings that. Then we have got the explosiveness coming off the bench with Tom Croft and Sean O'Brien.
"I don't know about not changing a winning side; it is about picking the best team to do the job for us.
"We can win this series by winning on Saturday and that is what our whole focus needs to be. The last thing we want to do is think about it being 1-1 and having to play another game in Sydney. Everything for us is about Saturday night."
Cuthbert drops to the bench, while Phillips is left out completely due to fears over a knee injury that has plagued the Welshman for the past few weeks.
Gatland added: "The decision was to rest him this week. He is potentially an important component for next week.
"Given the quality of the nines we have got, all of them have done a great job for us. We felt it was prudent to make sure he was 100 per cent fit for next week."
Lions XV for the second Test:
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)
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)