Middleweight contender Spike O'Sullivan (28-2, 20 KOs) says he is scheduled to return on September 15th, as part of the Canelo Alvarez-Gennady Golovkin undercard at the T-Mobile Arena in Las Vegas.

A few months ago, Sullivan was in serious negotiations to fight Golovkin for the WBC, WBA, IBO titles on May 5th at the StubHub Center in Carson, California.

While there were serious issues in making the Canelo-Golovkin rematch, O'Sullivan always expected the fight to happen.

O'Sullivan, who shares the same promoter as Canelo in Golden Boy Promotions, was promised a crack at the winner of the main event.

"I've always said that I thought the rematch would get made, the money involved is too good to turn down," O'Sullivan said to Sky Sports.

"I have a five-fight contract with Golden Boy, with three still remaining, and they promised me, after my last fight, that I would be on this September undercard before being in line to face the winner. I'm already working in the gym, but at the moment there's no talks of opponent but I expect a top undercard bout.

"It's all coming together nicely and I'm grateful for my fan base which continues to grow. I believe I'm at my best and coming into my prime. I've said many times before, 'you can't put an old head on young shoulders'. I train seven days a week now, all in the gym and I walk around at only a few pounds above my fight weight so I definitely think the best is yet to come for me in my career."

O'Sullivan appears to be leaning to Golovkin for the win in September - and he would really like to get Golovkin in the ring. The Irish boxer is very confident of beating him in the ring.

"The Golovkin fight was close, we were in talks and I wanted it, but it kept dragging on and they were talking to other fighters," 'Spike' continued.

"All my focus now is on September and then getting the winner. Canelo would, financially, be the bigger fight eventually, but I've always wanted to face 'GGG'. That's my dream fight, and I believe I can beat him and take his '0'."