Roger Federer extended his winning run to 19 matches with an easy victory at the Qatar Tennis Open while long-time rival Rafael Nadal was equally impressive in reaching the quarter-finals.
Federer, seeded second, routed Slovenia's Grega Zemlja 6-2 6-3 in an hour, dropping just 11 points in nine service games.
Top seed Nadal, who took two and a half hours to battle past first-round opponent Philipp Kohlschreiber, was more assured against qualifier Denis Gremelmayr as he strolled to a 6-2 6-2 win.
Like Federer, Nadal is looking to reclaim the world number one spot from Novak Djokovic.
The Qatar tournament is seen by both players as important preparation for this month's Australian Open, the first grand slam of the season, and the Spaniard has changed his approach to try to recapture top form, moving to the net a lot more than he has in the past and working on his returns which he described as worse than usual last year.
