Abel Sanchez, trainer of IBF, WBC, IBO, WBA middleweight champion Gennady Golovkin (37-0, 33 KOs), says Saul "Canelo" Alvarez will be one of the toughest fights of GGG's career.

Golovkin will defend his titles against Canelo on September 16th, during Mexican Independence Day weekend. HBO Pay-Per-View will carry the event.

Canelo was in action earlier this month, when he moved up to a catch-weight of 164.5-pounds to face Mexican rival Julio Cesar Chavez Jr. Canelo, fighting for the first time above a weight higher than 155-pounds, dominated Chavez Jr. over twelve rounds for a lopsided twelve round decision win.

The two boxers sparred several years ago at Sanchez's gym in Big Bear, California. Both of them have gotten a lot better since that session.

Canelo, 26-years-old, is in his prime and viewed as the biggest star in the sport. Golovkin, 35-years-old, is one of the most skilled and dangerous fighters in boxing, but some pundits believe the boxer is starting to show his age in the ring.

"[Canelo] will be one of the toughest. I think that his experience in the bigger fights — as Golovkin has had — is probably a forte for both guys. They’re not going to be nervous in front of a big crowd, no matter where the fight is. They’re not going to be unwilling to exchange because they know what they got. I think Canelo has a lot of very good attributes and so does Golovkin," Sanchez told On The Ropes Boxing Radio.

"It’s a fight where if it’s a long eleven or twelve round fight, I think it can be done again, they’re both very good fighters. The one thing about Canelo is that he has matured, he’s had some very good fights and he’s gotten better, he’s gotten better than when he was at my gym five years ago, and of course so has Golovkin. It’s the kind of fight that is coming at the correct time for both guys.