Parker will meet 28-year-old Flores in the ring in Christchurch on December 15 in a bout which could decide his future in the sport.
Nothing less than a knockout victory will be satisfactory for the Kiwi, a former WBO heavyweight world champion on the comeback after two consecutive defeats.
His team will hope their matchmaking due diligence on Flores, who has a 17-1 professional record, is on the money because a defeat at Horncastle Arena would be disastrous for Parker.
"With Joseph coming off two straight defeats – however unlucky – a third defeat would be catastrophic for his career," promoter David Higgins said. "Alexander's undoubted punching power makes this an extremely dangerous assignment for Joseph – so it is fair to say I am the most nervous I have ever been before a fight."
Parker, who began his training camp in Las Vegas two weeks ago, said he respected the danger posed by Flores.
"I'm really glad that Alex is coming to New Zealand full of confidence," Parker said. "For me boxing is all about the challenge – and this is another big one. I know what is stake, I need to win and win well. I need to knock him out and I will knock him out. But I can't focus on that. I need to focus on getting better each and every time I get in the ring."
Flores' only loss was against former IBF champion Charles Martin, a man with limited ability who went only one round with Anthony Joshua in London before the Brit knocked him over and out. Parker lost his WBO world title to Joshua but went 12 rounds in doing so.
But, predictably, the visitor, in Auckland on media duties, sounds confident.
"There is no way this fight goes 10 rounds," Flores said. "I'm going to knock him out.
"A lot of people might not have heard of Alexander 'The Great' yet – but they'll all know who I am after December 15."
One interesting side note is that Flores sparred with fellow American-Mexican Andy Ruiz Jr before the latter's challenge for the vacant WBO world heavyweight title won two years ago by Parker. Again, perhaps predictably, Flores believed the majority decision victory for Parker should have gone his compatriot's way.
Parker's trainer Kevin Barry, returning to his hometown of Christchurch, said: "After a five-year undefeated run that took Joe all the way to the WBO world title, we now find ourselves in very unusual territory, coming off back-to-back loses. Joe has never been in this position before and needs a top performance. Joe finds himself under huge pressure to not only to win this fight, but to win big and get his career back on track."
"We've known for some time it was likely to be Flores and it is great to have that confirmed," Barry added. "These guys are the same height and they both pack a serious punch, so it stacks up as a great contest. That's great for boxing fans – and Canterbury boxing fans in particular.
"This is a dangerous fight, a fight in which Joseph Parker is fighting for his career."
