Juan Manuel Marquez will try to match his brother Rafael by rising in weight and capturing a world title when he fights in Las Vegas on March 17 for the World Boxing Council super featherweight title.
The two-time world featherweight champion will face defending champion Marco Antonio Barrera in a duel of 33-year-old Mexicans.
The bout will be the 78th fight between two Mexican titleholders.
"It's the most important and most difficult fight of my career," Marquez said.
"I'm going to knock out Barrera. He has fought a lot but I'm at the peak of my career. It's time for him to retire and let me take the reins."
Marquez, 46-3 with one drawn and 42 knockouts, moves up as younger brother Rafael did last Saturday when he beat Mexico's Israel Vazquez for the WBC super bantamweight title, eight pounds below his brother's new 130-pound division.
"It was great. We all celebrated at home with the family," the reigning World Boxing Organization champion said.
"After seeing what he did, it's the motivation to be the champion at 130 pounds.
"Its controlled anger I will have up there. I'm going to be stronger at 130 pounds. I feel very good. I feel I have more speed now than I did before."
There is no sibling rivalry, the elder Marquez brother said.
"There's no rivalry. We both work hard and we both want to be champions," he said, noting they have not trained against each other in many years.
"Each time we trained they were wars. My dad had to step in and prevent us from sparring."
Barrera, 63-4 with 42 knockouts, has been a world champion in three weight classes in his 17-year career.
"Juan Manuel thinks he is going to knock me out. Let's see that happen," Barrera said.
"He's dreaming. Instead he should be training because I'm going to shut his mouth with punches not with words."