Iain Henderson left out with Lions team unchanged for third Test
The All Blacks have not lost at Eden Park since 1994, and have not lost a home Test series since 1986 - but head coach Warren Gatland firmly believes the Lions can now claim just their second-ever series win in New Zealand.
"This is a huge chance for this group of players to show their abilities and reap the benefits of the work everyone has put in," said Lions boss Gatland.
"It is their chance to make Lions history."
The ability to select pacy strike-runner Williams will be relief to Gatland, who has appeared happy with the balance of the back three after moving the Saracens-bound flyer into the 15 shirt for the Test series.
Williams did not complete Wednesday's training session at Queenstown Events Centre, with Lions kicking coach Jenkins later insisting: "It's probably precautionary, just a little bit of tightness."
It was Williams' gutsy break in the first Test that kick-started the 80-metre move for O'Brien's stunning try, and put New Zealand on message of the Lions' abilities and determination to play with width, pace and style.
The Lions lost the opening Test 30-15 at Eden Park, where the All Blacks have now gone 39 games without defeat.
But the tourists' nerve-jangling second Test triumph has teed up the chance to register a first series win over the All Blacks since 1971.
Gatland admitted he was pleased to be able to select the exact same match day 23 that featured in the second Test.
"It is not very often on a Lions tour that you get to pick the same 23 for the following game," said Gatland.
"We felt we should reward the players for the result and the courage that they showed in coming from behind from 18-9 down, digging themselves out of a hole and then finishing strongly in that last 10 to 15 minutes.
"There are some players who are pretty disappointed not to be selected and I understand that.
"It is what you would expect from competitive top athletes, they back themselves.
"But we have stressed all along that this is not all about the 23 players but about everyone in the squad. They have all put their disappointment behind them and are helping the match day squad prepare the best they can for the Test match.
"We are all aware of how big this game is and we are expecting a backlash from the All Blacks.
"But the pleasing thing about the second Test is just how strong we were in the last 10 or 15 minutes, in terms of energy and enthusiasm so we still feel there is another level in us."
The decision to stick with the same 23 as the second test means that Iain Henderson has again been left out of the squad - a decision that will disappoint those that felt the Ulster player had done enough to force his way into the squad.
New Zealand squad
New Zealand coach Steve Hansen named his squad earlier this evening, announcing that Jordie Barrett will make his first New Zealand start in Saturday's Test series decider against the British and Irish Lions.
Barrett, the 20-year-old brother of All Blacks fly-half Beauden Barrett, wins a second cap at full-back after going on as a replacement during the pre-series appointment with Samoa last month.
Elsewhere, Ngani Laumape lines up at centre instead of a suspended Sonny Bill Williams, while juggernaut wing Julian Savea is recalled for Rieko Ioane and Israel Dagg switches from full-back to right-wing, with Waisake Naholo dropping out.
Naholo suffered a head knock during the second Test defeat in Wellington last weekend, but it is understood his omission from the match-day 23 is not related to that.
Ioane, two-try star of the first Test win, also misses out, with Malakai Fekitoa, who was called into the All Blacks squad last weekend, providing back division cover on the bench alongside TJ Perenara and Aaron Cruden.
Both Barrett and Laumape have been in blistering Super Rugby form for the Hurricanes this year, but they are sure to come under pressure on Saturday, given their international inexperience, as the Lions target a first Test series triumph against New Zealand since 1971.
Savea, meanwhile, was not involved in the first two Tests, but he is a proven performer at the highest level, scoring 46 tries during his 53-cap career.
And All Blacks skipper Kieran Read becomes the seventh New Zealand player to win 100 caps, following Richie McCaw, Keven Mealamu, Tony Woodcock, Dan Carter, Ma'a Nonu and Mils Muliaina.
New Zealand head coach Steve Hansen said: "Firstly, on behalf of the All Blacks and all of New Zealand, I would like to congratulate Reado on reaching the milestone of 100 Test matches.
"It is a special achievement to play just one Test, so to play 100 is a remarkable effort.
"His playing ability speaks for itself and inspires others, and he now joins a unique group of special All Blacks.
"We would also like to congratulate Jordie on making his first Test start in what will be a very memorable occasion for him.
"This final match in the series is going to be a cracker. It's the series we expected it to be, as the Lions have quality players.
"It now comes down to this Saturday - the winner takes all - and that will create its own unique pressures, and it's going to be interesting to see how both sides cope with it.
"We've had a good week of preparation and are very excited by the opportunity that is ahead of us, and I am sure the Lions are as well.
"We know it will be a physical and intense match, but just as importantly, it will be a game where both teams will have moments of momentum, and the ability of everyone to adapt and adjust throughout the 80 minutes will be crucial."
Belfast Telegraph Digital