Timothy Bradley's trainer, Joel Diaz, took a swipe at Manny Pacquiao, saying that the former pound-for-pound king is already nearing the end of his illustrious boxing career.

Diaz told BoxingScene on Tuesday that Pacquiao will never be the same fighter he was before, saying that Pacquiao is now a shadow of the fighter who defeated the likes of Oscar De La Hoya, Miguel Cotto, Ricky Hatton, Marco Antonio Barrera and Erik Morales.

Diaz, who is currently preparing Bradley for his upcoming rematch with Pacquiao on April 12 at the MGM Grand in Las Vegas, echoed Bradley's previous statement, insisting that Pacquiao has lost his drive and killer instinct after losing to Juan Manuel Marquez.

"A lot of people are saying that Pacquiao is still bringing what took him to the top, but for me - Juan Manuel Marquez left his mark on him, with this knockout, it affected him," Diaz said, referring to Marquez's scintillating sixth-round knockout win over Pacquiao in their fourth showdown in December 2012.

The 41-year-old trainer added that Pacquiao looked indestructible during his prime, but he added that the former eight division champion has lost that aura, saying that the wear and tear of training has already taken its toll on Pacquiao.

"Manny Pacquiao was indestructible and he already lost that aura," Diaz said. "I do not have doubt that at the age of 36, already with 60 fights, 60 wars, and 60 preparations, the body is suffering from the work, the punishment, and there has to come the moment where you think about saying goodbye."

Pacquiao is coming off a unanimous decision win over Brandon Rios in November last year. The 35-year-old former champion looked dominant against Rios, but most experts were not impressed.

Rios' trainer, Robert Garcia, had the same opinion as Diaz, saying that Pacquiao is not, and will never again, be the same fighter that he was before his two straight defeats to Bradley and Marquez in 2012.

"With all the fights that he's had, the wars that he's had, it can't be the same anymore," Garcia said in an interview. "He can't be the same. We can hear it from his trainer. We can hear it from his manager. We can hear it from his sparring partners, from him himself - 'I'm in the best shape of my life.' That's never going to be true."