Sergei Derevyanchenko has been here before. The unbeaten opponent, the enticing prospect of a world title challenge, taking on a quality foe in a 50-50 fight.

The Ukrainian has never been one to back down from a challenge, which is why he says of his Saturday clash with Christian Mbilli that, “As soon as I heard about this match, I decided I’m going to sign up. This guy is the number one, and I’m going to give it a try.”

It's the same attitude that has seen him take on the likes of Gennady Golovkin, Daniel Jacobs, Jaime Munguia, Jermall Charlo, and Carlos Adames among others in his 20-fight professional career; but the downside of pursuing and facing the best is that victory is far from guaranteed, something that Derevyanchenko has found out to his cost. He ended up second best against each of the opponents listed above, leaving the 38-year-old Ukrainian with a professional ledger of 15-5 (10 KOs) that is arguably unrepresentative of his ability.

Yet while some contenders with similar records might in short order find themselves sliding further down the undercard or on increasingly obscure streaming sites, Derevyanchenko continues to feature in marquee matchups, such as the meeting with Mbilli, which is the main event of an ESPN card from Quebec City.

There are good reasons for that, of course. For one, Derevyanchenko is not just a quality contender, he’s an exciting one; known for his technical ability – his nickname is, after all, “The Technician” – he is nonetheless all but guaranteed to be on the front foot every time out. And those losses? Most of them have been agonizingly close. Flip a round or two here or there and the man from Feodosia could easily be 19-1.

His first defeat came in his 13th contest, a tilt for a vacant middleweight belt that had been taken from Golovkin, in one of HBO’s final fistic offerings in October 2018. The circumstances could not have been much more awkward: his opponent, Jacobs, was a long-time sparring partner and fellow disciple of Brooklyn-based trainer Andre Rozier, who elected to stick with Jacobs for this contest. (Gary Stark, Jr., a Rozier assistant, handled the Ukrainian’s corner.)

The evening got off to a bad start for Derevyanchenko when a Jacobs right hand caused him to touch the canvas in the very first round.

Already two points in the hole, Derevyanchenko sought to walk Jacobs down as the American worked behind his jab. In a close contest, both men had their moments; at fight’s end, one judge saw Derevyanchenko as the winner by the slim score of 114-113 while the other two gave it to Jacobs 115-112. 

It was a close loss, but not a controversial one: there was general consensus ringside that either of the official scores (or something in between) were acceptable, but that Jacobs had probably done enough to shade it.

Defeat number two was more contentious and perhaps the biggest “Sliding Doors” moment of Derevyanchenko’s career. Such are the vagaries of alphabet groups that the middleweight belt that had been taken from Golovkin and was claimed by Jacobs was once more vacant and on the line when the Ukrainian squared off against GGG in October 2019. It was Derevyanchenko’s second shot at a belt, and for the second time, he was dropped in the opening frame.

Once again, though, he came out strongly in the following round, and for the 10 rounds that followed. According to CompuBox, he hit Golovkin with more punches than had any of his previous opponents – including Canelo Alvarez. The Kazakh sounded afterward like a man defeated: “Right now it’s bad day for me, it’s a huge day for Sergiy, his team,” he said. But Golovkin was the one who walked away with the win by scores of 114-113 and 115-112 twice.

Derevyanchenko’s next outing was his third shot at a middleweight belt, and his third defeat – and arguably the only clear-cut loss of his career so far. Jermall Charlo was able to use his length and reach to keep Derevyanchenko largely at bay, while buckling him a couple of times as the Ukrainian pressed forward. This time, Derevyanchenko stayed on his feet, but the margins were wider than in his previous two title tilts, as Charlo took a unanimous decision by scores of 116-112, 117-111 and 118-110. Charlo, though, knew he had been in a fight: “I knew he was gonna be tough. I knew he was gonna come to fight,” he said afterward.

In December 2021, he fell to his third consecutive loss, and his fourth in five outings, when he dropped a majority decision to Carlos Adames in a middleweight title eliminator. Not for the first time, a slow start bedeviled him, as he lost each of the first four frames before storming back into contention over the middle part of the fight, only for the Dominican to step it up in the final couple of rounds and secure a 97-93, 96-94, 95-95 majority decision win.

Derevyanchenko’s most recent loss was both the most engrossing of them all and the one the Ukrainian is probably most likely to consider the one that got away. The Boxing Writers’ Association of America voted his 2023 scrap with Jaime Munguia as the Fight of the Year, and with good reason. In a fight of constantly shifting momentum, each man took it in turns to hurt the other, but entering the twelfth and final round, it was Derevyanchenko who held a narrow lead on two scorecards. 

But in the same way as first-round knockdowns let him down against Jacobs and Golovkin, a trip to the canvas in the twelfth denied him a win against Munguia, who uncorked a desperate but debilitating body shot to drop the Ukrainian: Derevyanchenko made it to his feet but spent much of the rest of the frame trying to hang on and recover. The scores, once again, were tantalizingly close: 115-112 and 114-113 twice for the Mexican.

And so now Derevyanchenko tries again. He has lost five of his last eight (although, if you prefer an optimistic outlook, he has won two of his last three), he is 38 years old and running out of time, and in Mbilli he is facing an opponent who may be stronger and fresher than any of his previous conquerors.

Mbilli knows what’s in store. He knows that he can expect the toughest night of his career. But he knows, also, that a clear, definitive win over Derevyanchenko would be a powerful statement that the likes of super-middleweight champ Canelo Alvarez would be hard pressed to ignore.

There is a sense that perhaps Derevyanchenko’s best opportunities have slipped through his fingers; Mbilli is a comfortable – 475 favorite on DraftKings as of Friday morning. But the Ukrainian knows better than most that the line between glorious winner and hard-luck loser is a thin one. One night, one fight, can make all the difference in a career; victory over Mbilli would potentially give him a fourth shot at a world title and a spectacular coda to a career that has glimpsed the promised land from afar without being able to reach it.

Kieran Mulvaney has written, broadcast and podcasted about boxing for HBO, Showtime, ESPN and Reuters, among other outlets. He also writes regularly for National Geographic, has written several books on the Arctic and Antarctic, and is at his happiest hanging out with wild polar bears. His website is www.kieranmulvaney.com.