ATLANTIC CITY, New Jersey – The last boxer to share a ring with Gary Russell Jr. believes his next opponent will upset boxing’s longest-reigning male champion.

Tugstsogt Nyambayar predicted during an interview with BoxingScene.com that Mark Magsayo will dethrone Russell in their 12-round, 126-pound championship match Saturday night at Borgata Event Center. Russell hasn’t lost in 7½ years and is consistently listed as at least a 4-1 favorite to beat Magsayo, the mandatory challenger for Russell’s WBC featherweight title.

“I have a very high opinion of Mark Magsayo,” Nyambayar said. “I think Mark will win the fight. He’ll win a decision.”

Russell (31-1, 18 KOs) – a smart, skillful southpaw from Capitol Heights, Maryland – is a better boxer than the Philippines’ Magsayo (23-0, 16 KOs). Nyambayar believes, however, that Magsayo’s style will prove to be too difficult for Russell, a 33-year-old fighter who hasn’t competed in nearly two years.

“Mark has stamina and he fights in and out,” Nyambayar said. “He gets in, boom! And then he gets out. Gary Russell will probably have a problem with that.”

Mongolia’s Nyambayar (12-2, 9 KOs) had various problems during his own 12-round title fight with Russell in February 2020. Russell won their battle between former Olympians by wide margins on all three scorecards at PPL Center in Allentown, Pennsylvania.

“He controls distance well, he’s fast and he’s a good counter-puncher,” Nyambayar said. “And he studies his opponents very well. He’s smart. He studies every aspect of his opponent’s boxing ability.”

Nyambayar wants a rematch with Russell, whom he now knows he approached in the wrong way.

“My footwork was a little off in that fight,” Nyambayar said. “I fought him at his rhythm. Instead of bringing the fight to him, I was chasing Gary Russell too much. He was dictating what happened. I was supposed to bring the fight to him.”

Russell and Magsayo will headline a “Showtime Championship Boxing” tripleheader.

The telecast is scheduled to start at 9 p.m. ET with a 10-round junior lightweight bout in which Nyambayar will box Namibia’s Sakaria Lukas (25-1, 17 KOs). Nyambayar was supposed to face Vic Pasillas, a southpaw, but he accepted the right-handed Lukas on less than one week’s notice because Pasillas (16-1, 9 KOs) tested positive for COVID-19.

“With the state of the world and how everything is, I have [Nyambayar] sparring right-handers and left-handers,” said John Pullman, Nyambayar’s trainer. “This happens, especially right now. You don’t know who you’re gonna fight until the bell rings. We focused on Pasillas, but he’s been sparring other guys in my gym that are right-handers as well.”

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