A wide-open scramble among heavyweights is underway, illustrated by a pair of world title fights in boxing's glamour division in an historic night for the sport in New York.
American Deontay Wilder puts his WBC title on the line against Artur Szpilka of Poland, and Ukrainian Vyacheslav Glazkov fights American Charles Martin for the vacant IBF crown.
The fight card marks the first heavyweight championship bouts staged in Brooklyn since 1900 when James Jeffries knocked out James Corbett in the 23rd round.
Wladimir Klitschko ruled the heavyweights for nearly 10 years but last November was shoved off his perch by Briton Tyson Fury, who scored a unanimous decision in Duesseldorf.
Fury collected the WBA, WBO and IBF belts but relinquished the IBF title by booking a rematch with Klitschko instead of fighting a mandatory IBF title bout.
That has reopened jousting for the prized honour of being undisputed heavyweight champion, last achieved by Lennox Lewis in 1999.
"To me it's really wide open," said Lewis.
"Wladimir Klitschko was the key. Everybody has been on the cusp, waiting for this opportunity. The crack has happened. Now it's open season for all the heavyweights."
Lewis described the new wave as "young, inexperienced", adding "there's three that really stick out. Tyson Fury, Dontay and (Briton) Anthony Joshua, maybe. I think they're all still learning."
Wilder (35-0 with 34 knockouts) and Szpilka (20-1, 15 knockouts), is trying to become Poland's first world heavyweight champion.
Glazkov, former Olympics bronze medalist takes a 21-0-1 record into the bout against Martin, 22-0-1.
Wilder said he was saving his actions for the ring.
"I don't want to say I'm gonna bash his head, or peel his melon back. I want my actions to speak for themselves," said Wilder, making his third title defence.
"The heavyweight division has definitely gotten exciting again," he added.
"I'm hungry for success. I want it all. I'm sick and tired of having interim champion, regular champion, super heavyweight champion. Too many belts going on. It's time to have only one."