Michael Cheika insists there will be no repeat of the violent scenes that marred the 2001 clash between New South Wales and the British and Irish Lions.
That game is still remembered for Waratahs full-back Duncan McRae punching Ronan O'Gara 11 times while the Irishman lay prone on the floor.
O'Gara required eight stitches in a facial wound while McRae received a seven-week ban.
"I think those days have gone," said current Waratahs head coach Cheika. "Even back then, it was over the top.
"But physicality can occur in lots of ways - rucks, scrums and the contacts have got to be big from our lads.
"We have to be big. We can't hope just to contain them, and we can't hold anything back. If we have that mentality over 80 minutes, we might put a bit of a dent in their tank.
"Anything in red that moves, we'll have a go at it."
Former Leinster boss Cheika will be without 10 players for Saturday's game. They are away with Australia currently preparing for the first Test against the Lions.
He has also has a number of players unavailable through injury, but added: "We certainly won't be going out there to look for a glorious defeat.
"If there is a one per cent chance we can win the game we'll take that one per cent and do what we can with it."
Cheika also dismissed suggestions the Lions might be under-prepared heading into Saturday week's Wallabies showdown, having only been seriously tested by the Queensland Reds from four starts on tour so far.
"They will be fine," he said. "They are the team that is playing games. Australia is the team that isn't playing games.
"I don't think there is any chance of the Lions being underdone. They've just had a full season, lads are being rested and he (Lions head coach Warren Gatland) has got good competition for places.
"All I can say is that what we need to do is try and put some doubt in the Lions minds before the following Saturday and help Australia's cause.
"I am not really sure how we'll do that, because on paper we are no match, but we have to try.
"You will never soften them up because they are hard guys. They are well conditioned. They are hard mentally, too. They've won Grand Slams, they've been in World Cup quarter-finals and semi-finals.
"I was involved with the development of some of these (Lions) players, and that makes me feel proud.
"That experience with Leinster is really helping me with what we are doing here. I learnt a lot about putting back into play some of the values of old school rugby.
"I am proud to have worked with those guys, but I will take the opportunity to cut a few of them down."