Will Adonis Stevenson retire if he loses to Badou Jack?

WBC light heavyweight champion Adonis Stevenson will face his toughest test in quite some time when he takes on former two-division world titleholder Badou Jack on Saturday at Air Canada Centre in Toronto.

But win or lose, this could be the last time we see Stevenson in the ring, or at the very least, retirement is approaching.

Both fighters tipped the scales Friday. Stevenson (29-1, 24 KO's), a Haiti native fighting out of Blainville, Que., weighed in at 173.4 pounds while Jack (22-1-2, 13 KO's), 34, a Las Vegas-based Swede, came in at 175 pounds on the dot.

Although Stevenson has yet to show visible signs of aging as a 40-year-old fighter, there is a famous saying in boxing that goes "Father Time Is Undefeated."

Stevenson might be at that point, he could be close, or perhaps we are witnessing another Bernard Hopkins-like run of a man who can continue fighting and win world titles late into his forties.

Hopkins (55-8-2, 32 KO's) currently holds the record as the oldest world champion in boxing history at 48 years of age. Not to take anything away from the living legend, but the competition in the 175-pound weight class at the time was not very impressive, with the exception of Sergey Kovalev, who handed Hopkins a one-sided defeat in November 2014.

Stevenson will not likely fight long enough to reach or even break Hopkins' record. That is because the light heavyweight division today is red hot, and there is a plethora of young, hungry fighters who desperately want to make their mark in the sport.

Artur Beterbiev. Dmitry Bivol. Oleksandr Gvozdyk. Marcos Browne. Sergey Kovalev. Joe Smith Jr.

These are some of the top fighters that the division has to offer and they combine for a record of 116-4-1 with 98 knockouts.

It may not end up mattering at all if Jack comes away as the victor and he very well could do that. It has been a while since Stevenson has been in a really challenging fight. He has not fought a mandatory since Tony Bellew in 2013.

Though Jack is coming in as the challenger, he is actually the one with the more superior resume. In his last six bouts, Jack has fought world class fighters like Anthony Dirrell, George Groves, Lucien Bute, James DeGal, and Nathan Cleverly.

Jack is an underrated, solid puncher. He became the first man to drop DeGale, he dropped Groves, and moved up to 175-pounds last August, and made it look easy with a fifth-round TKO of Cleverly to win a secondary light heavyweight world title.

But it could also come down to who lands the first hard shot. Stevenson and Jack each have one defeat, both were knocked out by a punch they did not see coming. However, they have yet to taste defeat since.

Stevenson was knocked out by a counter right hand from journeyman Darnell Boone, a journeyman who previously knocked down Andre Ward, in an April 2010 fight. Stevenson scored a sixth-round knockout in a March 2013 rematch.

Jack suffered a first-round TKO at the hands of Derek Edwards in February 2014 after he was caught with a wonderfully timed counter overhand right.

Stevenson's most lethal weapon is his left hand, while Jack is well-schooled, fundamental, and has power in both hands.

This fight will probably not go the distance. If Stevenson wins, retirement is not too far away. But if Jack wins, the retirement party could be coming a bit early.