By CARLOS ARIAS

BELL, CALIF. --- Juan Manuel Marquez admits he contemplated retirement after losing a split decision to Timothy Bradley last October in Las Vegas.

Marquez truly believed he deserved the decision against Bradley, but he is 40 years old.

"For me, this sport is a challenge," Marquez said at Azteca Boxing Club. "I want that fifth (world) title. The fifth title is my motivation. That's why I continue in this sport. (This) Saturday I have a tough fight."

Marquez has another big challenge when he faces Mike Alvarado in a catchweight bout at 144 pounds on Saturday night at The Forum on HBO.

"I don't know," Marquez said about how long he plans to continue fighting. "Right now, I don't think about retiring. I think (about) Alvarado. I think (about) the fight. Right now, I'm back fighting at The Forum. I star my career in this historic building. Right now, I feel like (I'm) 23 years old. I feel younger. I feel great. I don't have words to say."

Marquez cut his teeth fighting at The Forum. He had 12 fights at The Forum from 1995-99 and went 12-0 with nine KOs in those fights. Back in the 1990s, Forum Boxing promoted fighters such as Marquez and his brother, Rafael, Marco Antonio Barrera, Mark "Too Sharp" Johnson, Chiquita Gonzalez and Genaro "Chicanito" Hernandez. Marquez was among the breakout stars to come out of Forum Boxing, which was known for giving its fighters a baptism by far. The Forum was known as "The House of Upsets" in the boxing world back then.

"I remember when I fought Julian Wheeler," Marquez said. "He was an Olympian guy. Catalino Becerra and other great fighters (and) Puerto Rican fighters. I had difficult fights when I start my career at The Forum. My son watch the videos and he's (like), 'You look younger. You look good. What happen right now?' I remember great fights at The Forum."

Follow me on Twitter @PunchyMcGee.