The Irish centre, veteran of four Lions tour, was expected to captain the side in the most anticipated game in recent years following Sam Warburton‘s injury but instead Jamie Roberts will partner Jonathan Davies in the midfield with Manu Tuilagi providing the cover on the bench.
Roberts and Tuilagi missed the first two Tests due to injury are two of six changes in a starting XV that will now be lead by Welsh lock Alun-Wyn Jones.
Alex Corbisiero and Ricard Hibbard take over from Mako Vunipola and Tom Youngs at loosehead and hooker while Sean O’Brien is called in for Warburton at openside.
Following strong displays all tour, Toby Faletau is rewarded for his efforts starting at No.8 instead of Jamie Heaslip.
Mike Phillips returns at scrum-half with Ben Youngs, who started the last Test, dropped of the matchday squad all together as Conor Murray is on the bench.
Alongside Murray, Richie Gray brings his bulk to replace Tom Croft as second row replacement and Justin Tipuric covers the back row.
The Lions had the opportunity to clinch their first Series win since 1997 last Saturday but a late try from Adam Ashley-Cooper and a conversion from Christian Lealiifano won it 16-15 for the Wallabies to set up the decider in Sydney in three days.
Gatland said: “Brian was disappointed, but he appreciated that he was spoken to before the team announcement.
“It’s the first time that a coach has ever made the decision with him in 15 years of rugby. Jamie is back fit and has been given the nod in terms of his partnership with Davies.”
“It all comes down to Saturday. Winner takes all. We know we can leave nothing in the tank and that only a complete performance will get us across the line. Picking this team was not easy and ultimately with several players available after recovering from injury the head overruled the heart in many selection decisions.
“It has been a challenging tour and we have had our fair share of injuries but we always knew that would be the case. Brian O’Driscoll is a great player and has had a wonderful career but for the final Test in Sydney we just felt Jamie Roberts’ presence offered us something more.
“Mike Phillips and Alex Corbisiero were first Test selections and would probably have played in the 2nd Test if not for injury. Richard Hibbard, Toby Faletau and Sean O’Brien have also earned their starting places.”
British & Irish Lions: Leigh Halfpenny; Tommy Bowe, Jonathan Davies, Jamie Roberts, George North; Jonny Sexton, Mike Phillips; Alex Corbisiero, Richard Hibbard, Adam Jones; Alun Wyn Jones (Capt.), Geoff Parling; Dan Lydiate, Sean O’Brien, Toby Faletau.
Replacements: Tom Youngs, Mako Vunipola, Dan Cole, Richie Gray, Justin Tipuric, Conor Murray, Owen Farrell, Manu Tuilagi.