Del Potro lost only eight points while serving in a 6-3, 6-3 win over Carlos Berlocq. He needed just 66 minutes to complete the second-round win.
In addition to winning 80 percent of the points on serve, del Potro took half of the points and finished off four of his seven break chances when Berlocq served.
Ivan Dodig topped Tsonga 6-4, 7-6 (7-5) in a match that saw just four break-point chances. Dodig got the only break of the match in taking the first set and won all three of Tsonga's second-set break opportunities before closing him out in the tiebreaker.
Alexandr Dolgopolov dropped serve once in defeating eighth-seeded Janko Tipsarevic 6-3, 7-6 (7-2) and Jarkko Nieminen got by Michal Przysiezny 6-7 (4-7), 6-4, 6-2 by saving all eight of the break points he faced. That put Dolgopolov against del Potro and Nieminen versus Dodig in the quarterfinals.
Jeremy Chardy edged past Marco Chiudinelli 7-6 (7-2), 3-6, 7-6 (8-6) in a first-round match that took nearly 3 hours over two days. The match was suspended by rain Tuesday midway through the second set.
No. 3-seeded Milos Raonic beat Go Soeda 6-4, 7-6 (7-0) in the final first-round match.
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