DOHA, Qatar Rafael Nadal reached the semifinals of the Qatar Open after Steve Darcis of Belgium retired with a back problem Thursday while trailing 6-1, 2-0.Nadal, a two-time quarterfinalist in Doha, will meet Viktor Troicki of Serbia, who beat Lukasz Kubot of Poland 4-6, 6-4, 7-6 (1).”I am playing well,” Nadal said. “There was more confirmation that I am hitting the ball well. I started well and served good. I am in the semifinals without losing a set. I am happy with that.”Nadal broke Darcis three times in the first set, and again in the second game of the final set.”I wish him a fast recovery,” Nadal said. “I hope he is fit for the Australian Open.”Later Thursday, top-ranked Roger Federer plays Ernests Gulbis of Latvia and third-seeded Nikolay Davydenko of Russia faces seventh-seeded Ivo Karlovic of Croatia.(AP)

