While both advanced, they did it in very different ways. Nadal battled Philipp Kohlschreiber for more than 2 1/2 hours in a 6-4, 6-7 (2-7), 6-3 win. Nadal, No. 2 in the world and seeded No. 1 in Doha, lost his serve twice but still managed to run his career record to 8-0 versus Kohlschreiber.
Federer, seeded second, rolled over Nikolay Davydenko 6-2, 6-2 in 54 minutes. Federer opened the match with a break in a game that took 90 seconds and ended up dropping just nine points in eight service games. Federer, who beat Davydenko for the tournament title last year, is 16-2 lifetime against Davydenko.
No. 3-seeded Jo-Wilfried Tsonga outlasted Malek Jaziri 7-6 (7-5), 6-7 (5-7), 6-1. Neither player dropped serve until the third set when Tsonga got two breaks.
Unseeded players claiming first-round wins Tuesday included Denis Gremelmayr and Grega Zemlja, who earned second-round slots against Nadal and Federer, respectively.
Also advancing were Ivo Karlovic, Matthias Bachinger and Guillermo Garcia-Lopez.