Paris ? Shouts of bravo mingled with expressions of surprise as unseeded Mariano Puerta, an Argentine back from a nine-month drug suspension, and Nikolay Davydenko, a Russian on the rise, set up an unlikely French Open semifinal.

After nearly seven hours of tennis in a pair of five-set marathons Wednesday, Puerta and Davydenko emerged the weary winners who will face each other Friday for a spot in the final against the winner of the more celebrated semifinal between No. 1 Roger Federer and No. 4 Rafael Nadal.

Puerta outlasted No. 9 compatriot Guillermo Canas, 6-2, 3-6, 1-6, 6-3, 6-4, in a 3-hour, 35-minute match that was like an intense Argentine Davis Cup practice. The No. 12-seeded Davydenko gave himself a birthday present the day before he turned 24 by edging No. 15 Tommy Robredo, 3-6, 6-1, 6-2, 4-6, 6-4, in 3 hours, 18 minutes.

This was Puerta’s third tour event since returning from a suspension for testing positive for clenbuterol, a long-banned drug with anabolic properties that can build muscles and trim fat. An investigative panel determined that a doctor prescribed the drug to Puerta to treat an acute asthma attack.