The future Hall of Famer, 37, wasted no time getting to grips with overmatched mandatory challenger Cheyenne Hanson (17-3, 13 KOs), with the German's corner having seen enough before two rounds were complete.

During her post-fight interview, the Ring and unified champion sounded glad to deliver a statement of her skills against a bullish challenger almost a decade younger, who frustrated the veteran at Friday's weigh-in.

"She came to fight and came to win but this is my time. With the three minutes, we get to set up our shots, in the first round I was trying to figure her out and land my shots. When I went in the corner, I told Jordan [Maldonado, her corner] I got it, was just feeling her out but I've got it now."

After a competitive opening stanza, Serrano took control as the aggressor and Hanson couldn't evade capture.

Jabs stung her, before combination punches to head and body preceded a finish with the challenger pinned against the ropes and her corner frantically waving the white flag to referee Robert Hoyle's right on the ring apron.

"It gives us more time to have fun, that's what I was doing," she added when questioned about embracing the change to three-minute rounds, as almost all female boxers prefer the standardised two-minute frames instead.

When asked about who she wants next, the Puerto Rican was non-committal.

Ring and unified junior lightweight champion Alycia Baumgardner (18-1, 7 KOs) has been calling for her, as too has Ring and undisputed junior featherweight beltholder Ellie Scotney (12-0) more recently. Neither are likely to snare what could represent the 37-year-old's final fight, which she told ESPN she'd like in Puerto Rico or New York.

"The team does that, I don't know, I just train to fight, whatever my manager wants, I do. I'm happy to be [at] featherweight, I'm unbeaten here, feel the best and am unified champion."

At a time where rival Katie Taylor appears set for her final swansong at Croke Park in September, it feels fitting Serrano (49-4-1, 32 KOs) is looking to finish with a flourish herself having paved the way for many to seize the mantle within women's boxing.

"She is, without a doubt, the greatest Puerto Rican fighter of all-time - male or female. It's unequivocal, she's just tied the knockout record with Christy Martin and I know she's going to break it," MVP co-founder Jake Paul said.

"We're so proud of her here with MVP, couldn't be happier to be part of her career and have been here from day one supporting her on this grand rise, shoutout to Tito Trinidad and Miguel Cotto but this [Serrano] is the best."