By Lem Satterfield

Mexican middleweight challenger Julio Cesar Chavez Jr. spent much of Tuesday's national conference call on the defensive, even as the 25-year-old son of the former world champion by the same name vowed to be more offensive-minded during Saturday night's clash of unbeatens opposite WBC champion Sebastian Zbik of Germany at the Staples Center in Los Angeles.

"It just motivates me. To hear that all of these people are always doubting me as far as what I can do. Slowly and surely, I've been stepping into the ring against better competition and doing better all of the time," said Chavez, junior middleweight (36-2, 29 knockouts) and WBC Emeritus titlist Sergio Martinez (47-2-2, 26 KOs) sitting at ringside.

"I do want to prove that I'm capable of winning a world championship. I think that I'm ready for anyone, but first things first," said Chavez. "I have to win on Saturday to show that I'm capable of fighting those guys [Cotto and Martinez.] All that I need to do is win. I can't prove myself with words, it's got to be with my actions how ready I am for those guys."

Chavez Jr. fielded questions ranging from his father's expression of concern for his son, his knockout power and those concerning his intestinal fortitude given the fact that he did not come from the improverished backgrounds that his dad did due to his father's success.

"I don't think about losing. I'm positive. I'm mentally prepared to win. I come to win," said Chavez, in response to the query about Julio Cesar Chave Sr.'s concern were his son to lose to Zbik. "I know how important the fight is. I know how hard I've worked. To me, I'm just thinking of winning the championship."

It matters not, said Chavez Jr., that he did not face the rough and tumble upbringing of others, including his father, Floyd Mayweather and Manny Pacquiao, the latter of whom scrounged the streets for food as a youth.

Chavez Jr. said that he is no less motivated.

"I'm very hungry. To me, boxing is just something that I love do to. I grew up watching boxing. It's all that I saw all of my life. I saw how good boxing was to my father, and I always wanted to be a part of it somehow and in some way," said Chavez Jr.

"I want to make a name for myself. I'm very hungry to do something in this world and to be someone in this world, and I think that boxing is giving me the opportunity to do so," said Chavez Jr. "I'm hungry, I'm a young guy, and I want to win a championship just like any other boxer."

Chavez (41-0-1, 30 KOs) is coming off of January's unanimous 10-round decision over Ohio's Billy Lyell (23-9, five KOs) at Estadio Banorte in Chavez Jr.'s home town of Culiacan, Mex., his second under five-time Trainer of The Year, Freddie Roach, and strength and conditioning coach, Alex Ariza.

But perhaps Chavez's breakthrough performance had come in June of 2010, when he continued the family's winning tradition at at the Alamodome in San Antonio, Texas.

Although some 17 years after his father, Julio Cesar Chavez Sr., had fought to a 12-round, majority draw with Pernell Whitaker in September of 1993 at the same Alamodome venue, the son went one better with a one-sided, unanimous decision over New York's John Duddy (29-2, 18 KOs)

Against Duddy, who retired not long after the bout, Chavez Jr. had to overcome being staggered in the sixth round by sweeping the rest of the fight and winning, 120-108, 117-111, and, 116-112, respectively, on the cards of judges Juergen Langos, Julie Lederman and Glen Rick Crocker.

Chavez has scored one stoppage in his past seven bouts, that being a first-round knockout of Jason LeHoullier (21-5-1, eight KOs) in September of 2009.

Three fights prior to facing LeHoullier, there was Chavez's seventh straight knockout over light-hitting Tobia Giuseppe Loriga (24-2-2, six KOs), accomplished in the ninth round.

"This Saturday, I do want to give the fans a knockout, but if it goes to a decision, and I win, then that's okay too," said Chavez.

"I think that it has helped me, the experience of going all of those rounds," said Chavez. "I understand that in boxing, you can not always knock the other guy out. Sometimes you have to work and get a decision."

Roach was with eight-division king Manny Pacquiao (53-3-2, 38 KOs) in preparation for Pacquiao's May 7 unanimous decision defense of his WBO belt against over five-time titlist Shane Mosley (46-7-1, 39 KOs) before joining Chavez for Zbik.

The 29-year-old Zbik (30-0, 10 KOs) was elevated to the status of full WBC champion and mandated to face Chavez in his first defense in January, this after southpaw former titlist Martinez was declared the WBC's Emeritus Champion, essentially stripping the Argentinian-born fighter of the crown he earned by dethroning Kelly Pavlik (37-2, 32 KOs) in April of 2010.

"I know that he's [Zbik] dangerous, he's a world champion and I know that he's a great boxer and I know that he's coming to fight," said Chavez. "But just like this is the most important fight of my career, I know that this is the most important fight of his career because he wants to be well-known and this will give him that opportunity."