By DAN GELSTON
AP Sports Writer
NEW YORK (AP) — Botic van de Zandschulp has emerged as the surprise of the U.S. Open. The qualifier continued his out-of-nowhere run, beating No. 11 Diego Schwartzman 6-3, 6-4, 5-7, 5-7, 6-1 on Sunday at Louis Armstrong Stadium. Van de Zandschulp was part of a trio of U.S. Open qualifiers that reached the fourth round for the first time since the tournament began keeping qualifying records in 1982. He joined Nicolas Escude (1999) and Gilles Muller (2008) as just the third men’s qualifier to reach the quarterfinals since the Open era began in 1968. Before the U.S. Open, the ninth-year pro had only five tour-level wins, was never ranked higher than 117 in the world and had never advanced past the second round in a Grand Slam tournament.