Del Potro, the No. 1 seed in the tournament, blasted Marcos Baghdatis 6-1, 6-2. It was the third time this year the two have met and, while del Potro has won all three matches, this was the first not to go three sets.
Del Potro faced five break points -- saving all of them -- in the first set and still won 58 percent of the points in the set. He took two-thirds -- 76 percent when serving -- of the points in the second set.
Eighth-seeded Grigor Dimitrov needed only 61 minutes to beat Alexandr Dolgopolov 6-3, 6-2. Dimitrov didn't see a break point, losing nine points in his eight games serving.
Paul-Henri Mathieu earned a quarterfinal berth opposite del Potro with a 6-4, 6-3 win over Michael Llodra. Also Thursday, Edouard Roger-Vasselin topped Tobias Kamke 7-5, 6-3 while Daniel Brands was a 6-2, 6-4 winner over Lukasz Kubot and Vasek Pospisil defeated Ivo Karlovic 6-3, 6-4.
In addition to the del Potro-Mathieu matchup Friday, Roger-Vasselin takes on Brands in the other match in the top half of the draw. Pospisil meets Ivan Dodig and Dimitrov draws third-seeded Roger Federer in the other pairings.