French Open tennis champion Rafael Nadal of Spain and second seed Nikolay Davydenko of Russia have reached the third round of the Mercedes Cup clay-court tennis tournament in Stuttgart.

Nadal, the top seed, beat American Hugo Armando 6-1, 6-2. The win was Nadal's 30th straight victory on clay.

 Davydenko ousted Spain's Ruben Ramirez-Hidalgo in straight sets 6-4, 6-1. The Russian faces Germany's Alexander Waske, a winner over Jose Acasuso of Argentina (7-5, 6-4).

Another Spaniard, fourth-seeded Tommy Robredo fought back from a first-set loss to beat Italian Potito Starace in three sets (6-7, 6-3, 6-2). Robredo faces Andreas Seppi of Italy, a straight-set winner over Spain's Alberto Martin (6-4, 6-4).

Meanwhile, Czech player Jiri Novak - the tournament's sixth seed - ousted Razvan Sabau of Romania in three sets (4-6, 6-4, 6-0). Novak takes on Jarkko Nieminen of Finland, a three-set winner over Austrian Juergen Melzer (6-4, 6-7, 6-4).

Some information for this report provided by AP.