Delray Beach - Injury-nagged 2009 US Open champion Juan Martin Del Potro advanced on Thursday to the quarter-finals of the ATP Delray Beach Open by defeating Australian qualifier John-Patrick Smith 6-4, 6-4.
In only the second match of his comeback after sitting out for nearly a year, the 27-year-old Argentine wildcard entrant booked a last-eight date with French fifth seed Jeremy Chardy, who ousted American wildcard Noah Rubin 6-4, 6-2 in another second-round match.
"We've known each other since we were kids. He's a good friend of mine," Chardy said of Del Potro. "I was really happy for him to come back. For a tennis player, the worst is to be injured. We need players like him on the tour."
Del Potro, ranked 1 042nd in the world after missing most of the 2014 and 2015 seasons with a left wrist injury, underwent surgery last June and had not played an ATP match since last March until this week.
Smith, a left-hander ranked 135th in the world, was broken in the last game of the first set. He broke to lead 2-1 but Del Potro broke back in the fourth game.
The South American broke to lead 5-3 and served for the match but Smith broke back and served to pull level, only to have Del Potro end matters after 77 minutes when the Aussie netted a forehand.
Del Potro and Chardy, ranked 30th, have split two career meetings. Del Potro won a 2012 Cincinnati quarter-final but the Frenchman took a five-set triumph in the third round of the 2013 Australian Open.
US wildcard Tim Smyczek rallied to upset US seventh seed Donald Young 1-6, 7-6 (7/2), 6-2, setting up a quarter-final matchup against another compatriot, Sam Querrey.
Querrey went down a break early in each set but fought back both times for a 6-4, 6-3 triumph over American left-hander Austin Krajicek.
Friday's other quarter-finals will see French eighth seed Adrian Mannarino face Bulgarian fourth seed Grigor Dimitrov while American Rajeev Ram plays Germany's Benjamin Becker.