Hika Elliot will look to show off his boxing skills, while Paul Gallen says he will simply be doing his best when the pair square off in the boxing ring.
All Black Hika Elliot is targeting a knock-out, but says he wants to box, not brawl.
Kangaroo Paul Gallen says he doesn't know the difference between the two and he's simply looking to give it his best shot when he squares off with Elliot in the boxing ring.
The pair will tangle in a rugby-versus-league Fight for Life charity event in Auckland on Saturday night in aid of prostate cancer awareness.
There are seven fights on the card and the Elliot-Gallen bout is one of the two most intriguing.
The other attracting plenty of interest pits rugby ring-in Eric Murray, a London Olympics rowing gold medallist, with Warriors winger Manu Vatuvei.
Elliot weighed in on Friday at 113kg, giving him a 9kg advantage over Gallen.
The Chiefs hooker also has a karate record of 62-0, but says he hasn't fought for about four years and boxing is something different anyway.
However, he is looking for a quick finish to a contest scheduled for three two-minute rounds.
"I'll give it a good go," he said.
"You're not out there playing tiddlywinks. It's a charity event, but it's man versus man and, when we get into the ring, he's going to be trying to hurt me."
Elliot, 26, sees his speed as his forte.
"I just want to box and not try to make it a big brawl, because I'll be playing into his hands."
Meanwhile, Gallen said he had no idea what the weight difference would mean or what to expect when he climbed through the ropes.
"I haven't done it before and I don't really have a game plan," he said.
"I know in footy, the longer the game goes, the stronger I get. Maybe in the latter rounds, I'll get a bit stronger."
The NSW State of Origin skipper said he was probably suffering more nerves than before a football match, mainly because he was entering the unknown.
As to what his big weapon would be, the 31-year-old back-rower laughed.
"I've got two hands - that's about it," he said.
Three other Australians are on the card - Willie Mason, Greg Bird and Lauryn Eagle.
The other charity fights will pit Troy Flavell against Mason, Rene Ranger against Bird, and Carlos Spencer against Jarrod McCracken.
There are also two professional bouts, with Daniella Smith matched with Eagle, and up-and-coming heavyweight Joseph Parker facing his biggest test so far against the experienced Richard Tutaki.