Juan Manuel Marquez will be back in September to fight for a world title

Juan Manuel Marquez would be happy to fight Kell Brook in September, says his trainer Nacho Beristain.

The Mexican four-weight world champion is back in training and heading for the welterweight division, according to the man behind his success.

Marquez has lost to Floyd Mayweather, Manny Pacquiao and Timothy Bradley at 147lbs but also boasts a victory over Pacquiao at the same weight.

That success was a non-title fight, though, and Beristain reckons a belt at a fifth weight is high on Marquez's agenda, putting IBF champion Brook in the frame.

"I could see (Marquez returning) in September," he told Boxing Scene. "He looks forward to working in the gym. We have a singular joy whenever he steps in the gym. He works very hard.

"I don't know the opponent. I think a world title fight, a title in his fifth division, would be something he'd like."

Beristain mentioned Brook as a potential opponent, as well as "one of the other champions" -  WBA champ Keith Thurman and Floyd Mayweather, who holds the WBO and WBC versions.

The WBO belt could become vacant if Mayweather, who insists he will quit later this year after one more fight, is stripped.

Marquez has already challenged twice for that belt, but lost to Pacquiao in November 2011 and Timothy Bradley in October 2013.