Trainer Joel Diaz has warned that his hard punching boxer, WBA 'regular' welterweight champion Lucas Matthysse, could very well do some knockout damage on Manny Pacquiao.

The eight division champion will challenge Matthysse on July 14th at the Axiata Arena in Kuala Lumpur, Malaysia.

Back in 2012, Pacquiao was knocked out cold in the sixth round of his fourth bout with Juan Manuel Marquez.

Diaz is more than confident that Matthysse has more power and heavier hands than Marquez.

The veteran trainer expects the two fighters to trade punches during the contest, and that is when he believes Matthysse will do the most damage.

“Look, this is the thing: Manny Pacquiao has the speed, he has footwork and he has power too. But honestly, Manny Pacquiao is not a 147-pounder. He is a 135 and 140 pounder,” Diaz told The Manila Times in an overseas call. Lucas Matthysse has power. I believe Lucas Matthysse has the heavier hands than Juan Manuel Marquez.”

“In a little bit of exchanges of punches, it’s going to be hard for Manny Pacquiao to take a punch like that. He is no longer the young Pacquiao that can withstand power. The last fight was, as you can see, Marquez is a great counter puncher and Marquez, when he was hitting, is waiting for the right opportunity and right time to land on Manny Pacquiao and Manny Pacquiao came in. So a fighter like Matthysse with a harder punch than Marquez is dangerous for Pacquiao.”

Since Matthysse moved up to the welterweight division of 147, he's been trained by Diaz.

Matthysse made his debut at welterweight last May and knocked out Emmanuel Taylor. He came back in January and knocked out Tewa Kiram for the vacant WBA "regular" belt.

According to Diaz, his boxer's power will be the big difference in the contest.

“Lucas is a heavy puncher, a very heavy puncher. I trained Lucas Matthysse for his last two fights and he is one of the heaviest hitters that I trained,” explained Diaz.

“If Manny Pacquiao runs in to one of Lucas Matthysse’s right hand, he will get hurt because Lucas Matthysse has devastating power on his punches left and right. At this point of Manny Pacquiao’s career, he needs to be very careful. Because if he gets hit with a solid punch by Matthysse, he will be hurt.”