All Blacks lock Williams was passed fit at training today after lower back pain kept him out of Auckland's semifinal victory over Wellington in the capital last weekend.
His successful negotiation of contact training is likely to be enough to earn him a trip with the All Blacks to Europe next month, despite the fact he has played only two games since the second test against Ireland in June - both for Auckland in the ITM Cup - due to a knee operation.
He returned for Auckland against North Harbour and Otago before his latest problem.
The All Blacks squad for the tests against Scotland, Wales, Italy and England will be named in Christchurch on Monday morning and All Blacks coach Steve Hansen has suggested Williams only has to take the field for Auckland to get the nod.
"Ali is obviously very motivated. One, he is a proud Aucklander and he really wants to play his part. And secondly, he is very motivated to go on the end-of-season tour," Pivac said.
Asked how Williams had developed from his first days with the Auckland team as a teenager, Pivac said it appeared the now 31-year-old was a quick learner.
"In my eyes he changed from the very first time we dropped him from the team for some off-field shenanigans when he was 19. I've never had a problem with him since.
"I find him a character, I love having him in the environment. You don't really want 22 robots. At the end of the day you want a few dynamics. There's a lot of trainings, there's a lot of boring down-time in this game and a guy like that can liven it up when you need him to."
All Blacks prop Charlie Faumuina has been called in from holiday in Queenstown to provide cover on the bench following the thumb injury to Ofa Tu'ungafasi.
He was initially bracketed with Angus Ta'avao at tighthead prop but will start from the reserves after Ta'avao proved at training today that he is over a chest infection.
"We didn't anticipate having him," Pivac said of Faumuina. "We knew he was available but told him to take a few days off and he hasn't trained with us."
Faumuina will train with Auckland for the first time tomorrow before the flight to Christchurch.
All Blacks halfback Piri Weepu likewise is on holiday but will not be required.
In contrast, both of the All Blacks made available for Canterbury, props Wyatt Crockett and Ben Franks, have been named to start.
Captain Daniel Braid will become the first player since Eroni Clarke to play 100 games for Auckland when he leads out the team.
Teams for the ITM Cup premiership final at AMI Stadium in Christchurch on Saturday, kick-off 7.35pm
Canterbury: Johnny McNicholl, Telusa Veainu, Robbie Fruean, Tom Taylor, Willi Heinz, Tyler Bleyendaal, Andy Ellis, Luke Whitelock, Matt Todd, George Whitelock (c), Dominic Bird, Joel Everson, Ben Franks, Ben Funnell, Wyatt Crockett. Reserves: Codie Taylor, Joe Moody, Jed Brown, Jordan Taufua, Matthew Thatcher, Kolio Hifo, Stephen Gee.
Auckland: Charles Piutau, Ben Lam, Malakai Fekitoa, Hadleigh Parkes, Dave Thomas, Gareth Anscombe, Alby Mathewson, Joe Edwards, Daniel Braid (c), Steven Luatua, Ali Williams, Liaki Moli, Angus Ta'avao, Pauliasi Manu. Reserves: Nathan Vella, Charlie Faumuina, Nathan Hughes, Sean Polwart, Wayne Ngaluafe, Simon Hickey, Lolagi Visinia.
