Abel Sanchez, former trainer of IBF, IBO middleweight champion Gennadiy Golovkin, prepared the big puncher for his two fights with Mexican superstar Saul 'Canelo Alvarez.
The first time around, in September 2017, they fought to a controversial twelve round split draw.
A year later, Canelo fought his way to a close twelve round majority decision win.
Golovkin will return to the ring on Saturday night in Japan, when he faces WBA champion Ryota Murata in a three belt unification.
On May 7 in Las Vegas, Canelo will head up to the light heavyweight division to challenger WBA world champion Dmitry Bivol.
If Golovkin and Canelo win their respective fights, they will battle in a trilogy showdown in September.
Sanchez has a lot of respect for Canelo's abilities.
The veteran explains that Golovkin made a miscalculation on his strategy in the rematch, by utilizing a strict boxing game plan and allowing Canelo to come forward.
"[Canelo] can box, but he has a lot of his strength ......and I'm not talking about how strong he is. I'm talking about how strong his mind is, his body is strong, so he starts hunting you, he's a different fighter. He becomes someone different. I think in the Canelo fight, in the first one, [Golovkin] fought the way I wanted. In the second one, he wanted to be a boxer. He thought he could use his jab to win," Sanchez told Fight Hub TV.
"When a judge sees you go backwards, but normally you go forward, he thinks the [opponent is] hitting you. I think it was in the fourth round [of the second fight with Canelo], if you rewind the video, you can hear me say, 'You can't box this guy, you have to fight him.' I think he wanted to prove to everyone that he could box."