DELRAY BEACH, Fla. (AP) — Defending champion Sam Querrey reached the Delray Beach Open quarterfinals by hitting 13 aces and winning 24 of 25 first-serve points in a 6-2, 6-3 victory over Jared Donaldson on Thursday.
Querrey, ranked 35th and seeded No. 4, saved both break points he faced and took exactly an hour to beat his 20-year-old opponent in an all-American match at the hard-court tournament.
Querrey will face seventh-seeded Juan Martin del Potro of Argentina, the 2009 U.S. Open champion who beat Damir Dzumhur 7-6 (5), 4-6, 6-3 in the late match.
In other action, Donald Young followed up his upset of No. 2 seed Ivo Karlovic by coming back to eliminate 19-year-old Taylor Fritz 4-6, 6-3, 6-4 and get to the quarterfinals.
Young, ranked 69th, had his left knee checked by a trainer after only five games and wound up dropping that set. But Young managed to turn the match around despite finishing with 12 double-faults and facing 15 break points (he saved 13).