Juan Martin Del Potro turned back a challenge by Damir Dzumhur Thursday to book a quarterfinal clash with defending champion Sam Querrey at the ATP Delray Beach Open. Argentina's Del Potro, the 2011 Delray Beach champion playing just his second match of 2017, held on to beat the 24-year-old Bosnian 7-6 (7/5), 4-6, 6-3. Del Potro fired a backhand return wide to miss his first chance to seal the match, Dzumhur holding to make it 5-3 in the third. Del Potro gained another chance with a forehand crosscourt winner and secured the win when Dzumhur, scrambling back to defend a lob, missed a desperation between-the-legs attempt. Del Potro, the 2009 US Open champion now ranked 42nd in the world, is making his 2017 debut this week, and the rust was evident in six double-faults — five of them in the first set. That included two in the eighth game, in which he gave back a service break. On Friday, he'll face 35th-ranked Querrey, the fourth-seeded wildcard who blasted 13 aces without a double fault in dispatching fellow American Jared Donaldson 6-2, 6-3 in a second-round match at the outdoor hardcourt event. Also reaching the final eight was 57th-ranked Belgian qualifier Steve Darcis, who ousted Georgia's Nikoloz Basilashvili 6-3, 7-5. Darcis next faces 69th-ranked American Donald Young, who rallied to defeat compatriot Taylor Fritz 4-6, 6-3, 6-4. Monfils, Tsonga in last 8 Top-seeded Gael Monfils and No. 2 Jo-Wilfried Tsonga won in straight sets to reach the quarterfinals of the Open 13 Thursday. Monfils beat Sergiy Stakhovsky of Ukraine 6-1, 6-4 in less than an hour, and the Frenchman next faces countryman Richard Gasquet, who is seeded sixth. Tsonga, who won the World Tennis Tournament in Rotterdam last weekend for his 13th career title, downed Illya Marchenko of Ukraine 6-3, 6-3. Tsonga had nine aces and saved six break points, breaking his opponent's serve three times. Tsonga faces Gilles Simon in another all-French last-eight match. Russian Daniil Medvedev advanced after beating Germany's Jan-Lennard Struff 6-3, 3-6, 7-6 (3), and will face fourth-seeded Lucas Pouille of France in the quarters. Qualifier Norbert Gombos of Slovakia won against Nicolas Mahut 7-5, 3-6, 7-6 (5) and plays defending champion Nick Kyrgios of Australia Friday. Busta reaches quarters Fourth-seeded Pablo Carreno Busta has reached the quarterfinals of the clay-court Rio Open, defeating Victor Estrella Burgos 6-2, 4-6, 6-2. The Spaniard will face Alexandr Dolgopolov, who won his second-round match on Thursday against Horacio Zeballos 7-6 (4), 4-6, 6-4. Carreno Busta is one of only three seeded players remaining in the tournament, which saw top-seeded Kei Nishikori of Japan beaten in the first round. The favorite now is No. 2 Dominic Thiem, who will face Diego Schwartzman in the quarterfinals. No. 5 Albert Ramos-Vinolas will play Nicolas Kicker. — Agencies
