The 32-year-old was in Dunedin yesterday to help promote his first fight since March, when he beat Australian Hunter Sam to win the WBO Africa heavyweight title.
Tupou, who was born in Tonga but has lived in Australia since 1993, has put together a 25-3 record since his first professional fight in Australia in 2006.
He won his first nine fights there, before moving and fighting in the United States from 2007 to 2013.
Tupou won 13 of his first 14 fights in the US, before dropping two straight against Americans Malik Scott and Bryant Jennings.
Since moving back to Australia, the 1.89m boxer has won his last three fights but knows he needs to keep winning.
''I don't want to go home with an 'L' to my name,'' he said.
''This is my last chance. I have got to take this and make sure I win the fight. [Parker] is the person in front of me. He's going to try and take my opportunity away from me. So I have to take that away from him and eliminate him out of my path.''
Parker (14-0) was originally to have fought Japan champion Kyotaro Fujimoto, but Fujimoto pulled out of the bout after the New Zealander's devastating knockout of German champion Yakup Saglam in Palmerston North.
Tupou said a fight against Parker had originally been pencilled in for October, but was moved forward when Fujimoto pulled out.
While the Australian boxer believes Parker is ''raw and green'', he said the New Zealander would be his toughest opponent since losing to Jennings late in 2012.
''I have fought a lot of tough fighters in America,'' he said.
''Bryant Jennings, he was tough. He was physically tough and fit. It's about my experience. I've been through a lot and done that. Parker has only been through 14 fights.
''I'm going to use all my experience and the things I have been through and make sure we win this fight.''
Tupou and Basil Nassis, who is helping train Tupou with renowned boxing trainer Jeff Fenech, were in Invercargill on Wednesday.
It was not Tupou's first time there. He played rugby for an under-21 Penrith team, which played a number of games between Christchurch and Invercargill in 2001.
His side got ''hammered'' by Southland, but Tupou ''fell in love'' with Queenstown during the tour.
Nassis said he and Fenech were making sure Tupou was physically ready to go through ''12 tough rounds if need be''.
''Mentally, this guy is already there. He has been around boxing at a very high level.''
Tupou and Nassis will return to Sydney today to continue training, and are not expected to travel back to Invercargill until four or five days before the bout.
