The five-round title fight, Silva's first contest on home soil since 2003, marks UFC's return to Brazil following a 13-year absence.
The main event is a rematch of a 2006 bout which Okami (26-5) won by disqualification after Silva (30-4) illegally kicked him. Silva has rattled off 14 straight victories since the loss to Okami, and is widely regarded as mixed martial arts' pound-for-pound best fighter.
Weighing in to the strong audible support of his countrymen, Silva, 36, looked fit at 184 pounds. The 30-year-old Japanese challenger appeared to be in tremendous shape at 183 pounds.
"I'm going to do my best, and I'm going to take home the belt," Okami said to boos from the partisan crowd.
The UFC champion couched Saturday's anticipated card as "Brazil versus the rest of the world."
During his UFC debut in 2007, Rua (19-5) lost by third-round submission to Griffin (18-6). He rebounded to capture the UFC light heavyweight title, but surrendered the belt in March to Jon Jones.
Former Pride and UFC heavyweight champion Antonio Rodrigo Nogueira returns to the cage for the first time since February 2010 against newcomer Brendan Schaub. The Brazilian heavyweight legend stepped on the scale at 243 pounds, while Schaub, a 28-year-old American, seemed in fine shape at 247.
Rounding out the pay-per-view portion of the card, which kicks off at 9 p.m. ET, Luiz Cane (204) welcomes Bulgarian Stanislav Nedkov (203) to the UFC, and touted lightweight prospect Edson Barboza is matched against England's Ross Pearson.
Josh Gross covers mixed martial arts for ESPN.com.