Sam Querrey, Donald Young reach Delray Beach quarterfinals

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).

He then advanced to the semifinals when Belgium’s Steve Darcis withdrew from the quarterfinals because of personal reasons. Darcis beat Nikoloz Basilashvili 6-3, 7-5.