However, Gatland is adamant that the alterations he has made are tactical decisions and not due to form.
"This is a do-or-die match for Australia so we've decided to add some physicality to the side. Croft and O'Brien can give us explosiveness off the bench. The fact we've made five changes shows how strong the squad is. One or two changes have been forced on us by injury," Gatland told Sky Sports News.
"We said after the first Test that we had improvement in us and we are confident that this is the case. Several players have put their hands up this week and have forced their way into the Test side while several players have returned to fitness.
"That is typical of Lions tours. We want players to constantly push for selection, we then select who is on form and who is available. Based on that we have selected a squad that is capable of winning the Test and securing the series."