WINSTON-SALEM, N.C. (AP) -- Defending champion John Isner and top seed Jo-Wilfried Tsonga of France both won Tuesday in the second round of the Winston-Salem Open.

The third-seeded Isner, the highest-ranked American (10th) in the world rankings, was pushed to three sets before beating Slovakia's Martin Klizan 4-6, 6-3, 7-5.

Tsonga, the highest-ranked player (sixth) in the final hard-court tournament before the U.S. Open, beat Brazil's Thomaz Bellucci 6-3, 7-6 (7-2).

Also advancing to Wednesday's round of 16 were second-seeded Tomas Berdych of the Czech Republic, fourth-seeded Alexandr Dolgopolov of the Ukraine, sixth seed Marcel Granollers of Spain, seventh-seeded Sam Querrey, ninth-seeded Feliciano Lopez of Spain, No. 13 seed Jurgen Melzer of Austria, No. 14 seed David Nalbandian of Argentina and 16th seed Jarkko Nieminen of Finland.

Four seeded players were eliminated Tuesday: eighth-seeded Julien Benneteau of France, last year's Winston-Salem finalist; 11th-seeded Denis Istomin of Uzbekistan, 12th seed Kevin Anderson of South Africa and 15th seed Pablo Andujar of Spain.

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