Trainer: We haven't seen the best of Golovkin yet

As scary as unbeaten Gennady Golovkin’s reign of terror has been in the middleweight division in recent years, trainer Abel Sanchez offers an even scarier notion regarding his fighter’s future.

“Gennady has never really thrown a punch 100 percent in a fight like he does to me on the mitts,” Sanchez told ESPN.com.

This is Golovkin (33-0, 30 KOs) we’re talking about. The most avoided fighter in the sport who is arguably its most fearsome puncher. This is the same destroyer who has defended his middleweight title 14 straight times dating back to 2010.

If the idea that Golovkin, who has knocked out his last 20 opponents, has yet to discover how hard he can punch isn’t a big enough threat to his future opponents, Sanchez believes another truth will eventually be revealed.

“We haven’t seen the best of him,” Sanchez said. “I honestly think he still has yet to be challenged mentally, and that’s what is going to bring it out.”

Golovkin, 33, is expected to face the toughest challenge of his career when he meets hard-punching David Lemieux on Oct. 17 in a 160-pound title unification bout at New York’s Madison Square Garden (HBO PPV). But Sanchez disagrees.

One thing Sanchez does believe is that Lemieux (34-2, 31 KOs), with his relentless pressure style, offers enough of a threat compared to recent opponents to inspire a much more dangerous version of GGG on fight night.

“I think this is an opportunity for him to be motivated,” Sanchez said. “In the [Willie] Monroe fight, after the second round, I think [Golovkin] lost focus a little bit. It wasn’t difficult, so guys at this level, if they don’t have the motivation, they lose a little traction.

“So I think Lemieux, being perceived by everybody as being that kind of fighter, it will keep [Golovkin] motivated. This is the guy who can bring it out of him.”

Sanchez believes Golovkin lost focus and deviated from the game plan during his sixth-round TKO of Monroe in May. In the fight, Golovkin was hit more cleanly and often than in recent memory.

“He allowed Monroe to hit him with some shots," Sanchez said, "and I don’t know if it was the crowd or I don’t know if he wanted to put on a couple more rounds -- he never told me -- but I think in this fight he’s going to have to stay focused. If he stays focused, we are going to see those combinations that I see in the gym sometimes.”

In order for Golovkin to maintain that focus and unlock his full potential as a puncher, Sanchez believes it will come down to motivation, but not necessarily of the negative variety.

“It won’t be someone he’s mad at because against [Curtis] Stevens he didn’t want to knock him out, he just wanted to punish him,” said Sanchez, referencing Golovkin’s 2013 stoppage win after prefight trash talk from Stevens.

“So it has to be somebody who motivates him, like Floyd [Mayweather], because that will give him that notoriety and that legendary look from the world. With Floyd, if you remember the first [Jose Luis] Castillo fight, I don’t know if he had an off night, but the next fight he was totally different. The same thing with [Marcos] Maidana -- he has to be challenged.”

A Mayweather-Golovkin fight would be one of the most anticipated in the entire sport, although it remains unlikely, even with GGG's insistence that he could comfortably make 154 pounds. Sanchez gets visibly excited at the notion, explaining how exciting superfights are for the trainers, as well.

“I think that fight for a coach -- obviously Gennady and Floyd would be fighting -- but the coaches are fighting each other too,” Sanchez said. “For us to be able to put a game plan together that thwarts everything Floyd is doing would be exceptional, and a dream come true for a coach also.

“So that would be very exciting, but I don’t rule it out completely. Roberto Duran went up two divisions and beat Ray Leonard and then went up two more divisions and beyond. And he’s no more bigger than Floyd.”

Sanchez believes that if Golovkin defeats both Lemieux and the winner of November’s Miguel Cotto-Canelo Alvarez showdown, then a Mayweather-Golovkin fight would be even bigger at that point than Mayweather’s victory over Manny Pacquiao in May that set just about every financial record.

And if Golovkin can continue to secure bigger fights against increasingly dangerous opponents, Sanchez believes we will get that much closer to finding out just how great his pupil can be.

“There’s a saying that this kid is not the best defensive fighter, but it’s only because we haven’t had to see that yet,” Sanchez said. “He’s not the most destructive fighter yet because we haven’t had the chance. When he fought Stevens, he wanted to punish Stevens. When he fought [Marco Antonio] Rubio, he put him away so quick. So when he fought [Monroe] and [Martin Murray] he wasn’t as interested. And you could see that.

“But a guy with Mayweather’s credentials or even [Lemieux], it just gives him a little more animation, and hopefully he understands that this fight sets up everything that we will do in the future. How he does and what he does to Lemieux will determine the paycheck he gets for the next fight.”