|Collin Altamirano, shown in 2014, defeated fellow|
qualifier Karue Sell 7-6 (5), 7-5 in Los Angeles.
Photo by Paul Bauman
In a matchup of diminutive former NCAA singles champions from UCLA, No. 5 seed and San Francisco Bay Area product Mackenzie McDonald topped Marcos Giron 6-7 (4), 6-1, 6-2.
Altamirano, who ousted top seed and 2015 French Open junior champion Tommy Paul in the first round, will play No. 8 seed and University of Virginia teammate Carl Soderlund of Sweden.
Soderlund beat another Virginia player, Thai-Son Kwiatkowski, 7-5, 7-5.
Altamirano, a junior, has starred on two NCAA championship teams at Virginia. He won the 2013 USTA boys 18 national title, earning an automatic wild card in the U.S. Open, and reached the 2014 final.
Soderlund is a freshman at Virginia.
McDonald, who grew up in Piedmont, will meet No. 2 seed Roberto Quiroz, a former USC All-American from Ecuador.
Quiroz dispatched qualifier Henrik Wiersholm, a junior at -- you guessed it -- the University of Virginia, 6-2, 6-4.