Nadal and Federer dig deep to make quarter-finals

DOHA // Rafael Nadal, the top seed and world No 1, shrugged off the effects of a fever and a shock second-set whitewash to battle past Lukas Lacko and book his place in the quarter-finals of the Exxonmobil Open in Doha yesterday.

Nadal looked to be heading for an early exit when he won just 11 points in the second set before fighting back to claim a 7-6, 0-6, 6-3 win over the Slovakian.

Roger Federer, the world No 2 and twice Doha champion, was also required to work overtime for his last-eight place, before recording a 7-6, 7-5 win over Swiss compatriot Marco Chiudinelli.

Jo-Wilfried Tsonga, the third seed, took just under 75 minutes to defeat Sergei Bubka, the Ukrainian wild card, and Latvian Ernests Gulbis, the fifth seed, beat Antonio Veic, the Croatian qualifier, 6-3, 6-1.

Tsonga is a possible semi-final opponent for Federer. "He's a wonderful player, a great character," the world No 2 said of the Frenchman.

"He has performed well at the big tournaments, especially on the hard surface at the Australian Open. Unfortunately, he's had injuries and didn't play as much but he's tough."

The big-serving Ivo Karlovic hammered down 28 aces en route to knocking out Philipp Kohlschreiber, the German eighth seed, 7-6, 6-7, 7-6 after a clash in which there were no breaks of serve.

Serbian Victor Troicki, the sixth seed, is next up for Federer after a 6-3, 6-1 win over Russia's Teymuraz Gabashvili, while Guillermo Garcia-Lopez, the seventh seed, eased past Ukraine's Ilya Marchenko 6-1, 6-4.