Both hope that a win results in a fight against the winner of Floyd Mayweather vs. Canelo Alvarez - the main event.
Matthysse, through a translator, said he has "no worries" about Garcia.
"He's not a very good boxer," Matthysse said. "He's a fighter that's aggressive and comes forward just like I do. I like that."
He said he can take Garcia's left hook, the same one that Amir Khan, too, said he could take before being leveled last summer. If Garcia drops him, Matthysse said, he will get up.
"I'm not even worried about him," the 25-year-old Garcia said. "He's obviously scared if he's talking about me."
Matthysse (34-2, 32 knockouts) turned professional in 2004, and 25 of his first 28 fights were in South America. His first loss was a 2010 split decision in Newark, N.J., against Zab Judah, a fighter Garcia (26-0, 16 KOs) beat by unanimous decision in April.
Matthysse split his next two fights but has won his last six by stoppage.
He is working on his boxing but said he has not been able to show it because his opponents are always on the run.
And against Peterson he showed his newest accessory: a strong right hand that accompanies his devastating left hook.
That combination, Matthysse hopes, could be what again turns a champion into just another fighter.
"It's the fight of my life," Matthysse said. "And I'm going to take advantage of it."
The telecast will begin at 9 p.m. Saturday on Showtime pay-per-view from the MGM Grand in Las Vegas. Danny Garcia's bout will start about 10:30 p.m.
Ashley Theophane (33-5, 10 KOs) vs. Pablo Cesar Cano (26-3-1, 20 KOs), 10 rounds, welterweights.
Ishe Smith (25-5, 11 KOs)
vs. Carlos Molina (21-5-2, 6 KOs),
12 rounds, light-middleweights.
Danny Garcia (26-0, 16 KOs)
vs. Lucas Matthysse (34-2, 32 KOs), 12 rounds, light-welterweights.
Floyd Mayweather Jr. (44-0,
26 KOs) vs. Canelo Alvarez (42-0, 30 KOs), 12 rounds, light-middleweights.
Contact Matt Breen at email@example.com. Follow on Twitter @matt_breen.