Sam Riffice of Roseville in the Sacramento area surprised No. 10 seed Jurabek Karimov of Uzbekistan 6-3, 6-3 on Thursday in the second round of the boys 18s in the Orange Bowl in Plantation, Fla.
Riffice, who trains at the USTA center in Boca Raton, Fla., won the boys 16 title last year at 15 years old. He is scheduled to play Toru Horie, 16, of Japan today for a quarterfinal berth in the clay-court tournament.
Horie upset seventh-seeded Felix Auger-Aliassime of Canada 6-3, 6-4. Auger-Aliassime, 15, won last week's Eddie Herr International Tennis Championship in Bradenton, Fla.
The winner of the match between Riffice and Horie will play again today, probably against No. 2 seed Mate Valkusz of Hungary, for a semifinal spot.
No. 1 seed Casper Ruud, 16, of Norway edged Alexandar Lazarov, 18, of Bulgaria 4-6, 6-4, 7-6 (5). Ruud's father, Christian, climbed to a career-high No. 39 in the world in 1995.
Riffice's friend and neighbor from Roseville, Keenan Mayo, lost to No. 1 seed Jonas Eriksson Ziverts of Sweden 6-2, 6-4 in the second round of the boys 16s.
But Mayo and Trey Hilderbrand of San Antonio knocked off top seeds Eriksson Ziverts and Karl Friberg, also from Sweden, 6-4, 6-0 to become the only unseeded team in the doubles quarterfinals.
Mayo trains at the USTA center in Carson in the Los Angeles region.
Michaela Gordon, 16, of Saratoga in the San Francisco Bay Area had a big day in the girls 18s. Seeded 12th in singles, she beat Nina Kruijer of the Netherlands 6-4, 6-1. Then Gordon and Jaqueline Cristian of Romania ousted No. 4 seeds Charlotte Robillard-Millette and Katherine Sebov of Canada 6-2, 2-6 [10-4] to reach the doubles quarters.
Gordon will face No. 7 seed Evgeniya Levashova of Russia today. The survivor will play later in the day, likely against No. 2 seed and reigning U.S. Open girls champion Dalma Galfi of Hungary, for a semifinal berth.
Carolyn Campana of Hillsborough in the Bay Area lost to seeds in straight sets in the second round of girls 16 singles and doubles.
Also in girls 16 doubles, Abigail Forbes of Raleigh, N.C., and Jessi Muljat, 14, of Sacramento fell to No. 4 seeds Ania Hertel of Poland and Mihaela Lorena Marculescu of Romania 4-6, 6-2 [14-12].
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).