Riffice, who won the 16s title last year at 15 years old, will face 10th-seeded Jurabek Karimov of Uzbekistan. Karimov demolished lucky loser Sean Huynh of Canada 6-1, 6-0.
Riffice trains at the USTA center in Boca Raton, Fla.
In the first round of the boys 16s, Jenson Brooksby of Carmichael in the Sacramento region lost to qualifier Luka Pavlovic of France 7-6 (5), 7-6 (3). Brooksby, 15, served for the second set at 5-4.
Sofia Kenin, the top seed and defending champion in the girls 18s, fell to Olga Danilovic, a 14-year-old left-hander from Serbia, 6-0, 5-7, 7-5.
No. 12 seed Michaela Gordon (girls 18s) of Saratoga in the San Francisco Bay Area, Carolyn Campana (girls 16s) of Hillsborough in the Bay Area and Keenan Mayo (boys 16s) do not play singles today after winning their first-round matches earlier in the week.
Gordon, 16, reached the Wimbledon girls quarterfinals this year. Mayo, Riffice's childhood friend from Roseville, trains at the USTA center in Carson in the Los Angeles region.
Mayo will take on second-seeded Jonas Ericksson Zeverts of Sweden. Campana will meet ninth-seeded Sohyun Park of South Korea.
The Orange Bowl, the top junior tournament in the world outside of the Grand Slams, was founded by Eddie Herr in 1947. It was played on clay until 1998, then on hardcourts until 2011. It has been contested on clay again since then.
Past winners of the Orange Bowl 18s include Chris Evert (1969-70), Bjorn Borg 1972), John McEnroe (1976), Ivan Lendl (1977), Gabriela Sabatini (1984), Mary Joe Fernandez (1985), Jim Courier (1987) and Anna Kournikova (1995).
Winners of the tournament on hardcourts include Roger Federer (1998), Elena Dementieva (1998), Andy Roddick (1999), Vera Zvonareva (2000 and 2001), Marcos Baghdatis (2003) and Caroline Wozniacki (2005).
In Plantation, Fla.
(Northern California results only)
Sam Riffice, Roseville, def. Andres Andrade, Ecuador, 4-6, 6-3, 6-2.
16-and-underKeenan Mayo, Roseville, def. Palaphoom Kovapitukted, Thailand, 6-3, 6-2.
Luka Pavlovic, France, def. Jenson Brooksby, Carmichael, 7-6 (5), 7-6 (3).
18-and-underYuta Shimizu and Yunosuke Tanaka, Japan, def. Sam Riffice, Roseville, and Vasil Kirkov, Tampa, Fla., 7-6 (2), 6-3.
16-and-underTrey Hilderbrand, San Antonio, and Keenan Mayo, Roseville, def. Harrison Brown, Australia, and Vikash Singh, India, 6-3, 6-2.
Charles Fischer Pinheiro and Gilbert Soares Klier, Brazil, def. Jenson Brooksby, Carmichael, and James Ignatowich, Delray Beach, Fla., 6-3, 7-5.
18-and-underMichaela Gordon (12), Saratoga, def. Maria Jose Portillo Ramirez, Mexico, 6-3, 6-0.
16-and-underCarolyn Campana, Hillsborough, def. Luniuska Delgado, Venezuela, 7-6 (5), 6-3.
Eunhye Lee, South Korea, def. Jessi Muljat, Sacramento, 6-3, 6-0.
18-and-underJaqueline Cristian, Romania, and Michaela Gordon, Saratoga, def. Isolde De Jong and Nina Kruijer, Netherlands, 6-3, 3-6 [10-7].
Abigail Forbes, Raleigh, N.C., and Jessi Muljat, Sacramento, def. Sandra Aguirre and Sofia Ayuso, Venezuela, 6-1, 6-1.
16-and-underCarolyn Campana, Hillsborough, and Jayci Goldsmith, Austin, Texas, def. Luniuska Delgado, Venezuela, and Mell Elizabeth Reasco Gonzalez, Ecuador, 7-6 (6), 6-3.