Delray Open: Juan Martin Del Potro beats Damir Dzumhur, books quarter-final clash with Sam Querrey

Florida: Juan Martin Del Potro turned back a challenge by Damir Dzumhur Thursday to book a quarter-final 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.

Del Potro fought off a set point to force the tiebreaker and after securing the first set seized a 3-1 lead in the second only to again give back a service break.

A double fault on break point at four-all cost the Argentine a second break of serve and, one game later, the set.

But once he`d broken to seize a 4-2 lead in the third, Del Potro wouldn`t again surrender the advantage.

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.