Playing for the Barbarians at Wembley last December in the tour-ending match, Jack said the influence of his former Crusaders coach was unmistakable from the previous time he'd faced Australia in 2007.
"He's just toughened them up. He put a lot more expectation on their defence and put a lot more pressure on their performance," Jack said.
"They seemed a lot prouder. I'm not saying they weren't proud before but he put a lot of pressure on them to perform and to be proud of their performances."
The Wallabies won a bruising encounter 18-11 last December and face an intense rematch at the Sydney Football Stadium tomorrow night against a touring team with seven recent All Blacks and former Kiwis league star Sonny Bill Williams.
It's the first outing of the season for Deans' full-strength side in year two of his trans-Tasman journey, while the powerful Barbarians are eager to make it back-to-back international wins after they toppled England 33-26 last weekend.
While Jack -- returning from England to New Zealand with five-eighth Luke McAlister to chase an All Blacks jersey -- admitted that the team had "got into the Barbarians lifestyle" in the past fortnight, there was a quiet confidence they could upset the hosts.
"The guys who play for the Barbarians love it and always seem to play pretty well. Most teams underestimate them and they do well.
"It suits us, we have a good time and we normally do them pretty proud."
The Barbarians have depth all over the field and some inside intelligence, with captain Phil Waugh and fellow Wallaby Rocky Elsom forming a tough loose forward trio with former All Black Jerry Collins.
The 48-test All Black Collins admitted fitness and advancing years might be their biggest handicap.
"It was bloody fast (in December) and it'll be fast on the weekend. They play an expansive game and keep the ball alive with players who can offload," he said.
He admitted there's been a few more social engagements with the Barbarians than in test week with the All Blacks, but that would mean little at kickoff.
"When 40,000 people turn up to watch you it's pretty serious. Our preparation's not as serious as Australia but, trust me, we take it seriously.
"Hopefully we'll have most of the ball and they'll be doing most of the tackling. We won't be holding anything back, we've got our pride as well and we want to do well. And we definitely don't want to lose to Australia."
Young Wallabies No 8 Richard Brown, who combines with Wallabies debutant flanker Matt Hodgson tomorrow, predicted it would be as intense as a test match.
"I reckon I was broken for a good three weeks after that game," he said of the Wembley encounter.
