Claressa Shields cannot comprehend how she is viewed as the underdog in certain circles entering her long-awaited showdown with Savannah Marshall.

Though her British rival beat her in an amateur match 10 years ago, Shields went on to win two Olympic gold medals, became a three-weight world champion as a professional, was the fully unified champion in two of those divisions and hasn’t lost a boxing match since Marshall out-pointed her 14-8 at the AIBA World Women’s Boxing Championships in May 2012. Marshall, meanwhile, appears to have received more attention for defeating Shields as an amateur than for winning a then-vacant WBO middleweight title in October 2020 that only became available because Shields dropped down from the middleweight division to compete as a 154-pounder.

Shields expressed some dismay during a press conference Thursday in London, where she reminded Marshall and others of the undeniable differences between their careers as amateurs and professionals.

“It’s gonna feel good to just kinda quiet all the doubters about, you know, this knockout power and the lack of my skill and the lack of my accomplishments, or whatever the case may be,” Shields said. “Because, you know, I’ve never seen something like this in boxing before. Not the all-women’s card, because that’s magnificent. But someone who lives off of an amateur win for 10 years. God!

“I mean, sometimes I think about it and I’m like, it’s like they’re trying to erase everything I’ve done in the past 10 years because I have been dominant in boxing for a decade, since I was 17. I didn’t win the Olympics and then just have a terrible career. It’s like, I won the Olympics, I won it again, I turned pro, I won titles and it’s just like, ‘Wow! It’s still not enough for you guys. OK.’ ”

Whereas the outspoken Shields isn’t shy about expressing her opinions, Marshall is quiet and reserved.

“The Silent Assassin” wouldn’t even specifically predict a knockout Thursday. Marshall would only say that she’ll “hurt” Shields and leave her opponent to “wake up on the canvas.”

Marshall, 31, did indulge Shields in some trash talk Thursday, but the WBO champion is much more focused on proving she is the superior fighter in their 10-round, 160-pound full unification fight for the IBF, WBA, WBC and WBO middleweight titles Saturday night at O2 Arena in London.

The fans figure to heavily favor Marshall (12-0, 10 KOs) in her home country, yet that disadvantage has only provided more motivation for Shields (12-0, 2 KOs).

“I’m here to fight against who [the] UK considers the best,” said Shields, who was listed as a slight favorite Thursday by Caesars Sportsbook. “I’m here to fight against who [the] UK considers the knockout puncher, right? And I’m here to show you guys that I am a very special talent, that champions are not made, they’re born, and that I was born to do this. So, that’s why I’m here. I’m happy to be here with the naysayers and the doubters and the fans. I love you guys. It’s gonna be a great show and you will all be fans after.”

The 27-year-old Shields has dismissed Marshall’s high knockout ratio (83 percent) as mostly a byproduct of opportunistic matchmaking. The self-professed “GWOAT,” short for “greatest woman of all-time,” insists that Marshall mostly has feasted on smaller, overmatched opponents, many of whom have agreed to box Marshall on varying degrees of short notice.

Still, Marshall seemingly is the puncher in this bout, as Shields has gone the 10-round distance in eight straight fights, albeit against a higher level of opposition. Regardless, Shields feels her superior skills, intelligence and athleticism will enable her to dominate the taller, rougher Marshall.

“When I win on Saturday night, it’s gonna be, you know, it’s gonna be a great victory for me,” Shields said. “I know that this isn’t my first undisputed fight. This isn’t my first time having a very, very hard training camp and being the underdog. This isn’t my first time. I’ve done this numerous of times and I’ve come out on top every time.”

If the show is allowed to move forward, then the 10-round grudge match between Shields, of Flint, Michigan, and Marshall, of Hartlepool, England, will headline a Sky Sports telecast set to start at 7:30 p.m. BST in the United Kingdom and Ireland. ESPN+ will stream the Shields-Marshall card in the United States, where its coverage is scheduled to begin at 2:30 p.m. ET.

The entire card is potentially being postponed to a later date - due to a period of mourning in connection with Thursday's passing of Queen Elizabeth II. The boxers are scheduled to make weight on Friday - in the event the anticipated card is permitted to proceed.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.