Roger Federer extended his winning run to 19 matches with an easy victory at the Qatar Open on Wednesday while longtime 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.
"I'm happy to come through matches easily at the beginning of the season, because it can be tricky when you enter the first tournament and right away you play an incredibly tough three setter," Federer said in a post-match news conference.
Top seed Nadal, who took two and a half hours to battle past first-round opponent Philipp Kohlschreiber on Tuesday, was more assured against qualifier Denis Gremelmayr as he strolled to a 6-2, 6-2 win.
The unfancied German had won a solitary game in their only previous meeting and fared little better in windy Doha, Nadal pounding his fellow left-hander from the outset.
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.
"I went to the net a lot of times, that's important. It's something we are trying to do more often," said Nadal.
"I'm trying to return a little bit better, because for me the worst thing that I did last year was the return, especially the second half of the year. My return was worse than usual."
Nadal had been troubled by a shoulder injury for several weeks but there was little sign of this as Gremelmayr, ranked 189 in the world, was forced to save a break point in the opening game.
The German lost his next service game, a poor forehand into the net putting Nadal 2-1 ahead and a break up.
Serving at 1-3 down, Gremelmayr saved three break points in a game of seven deuces, but the 30-year-old then stabbed a forehand passing shot into the net to give Nadal a fourth opportunity.
The 10-times Grand Slam winner took it with a thumping forehand the despairing German could only shovel into the net for a double break and a 4-1 lead.
The second set was similar, Nadal breaking immediately as he raced into a 4-0 lead before serving out the set.
French duo Jo-Wilfried Tsonga, seeded third, and Gael Monfils joined them in the last eight.
Tsonga came from a break down and also saved two set points in a first set tiebreak against Flavio Cipolla, eventually defeating the Italian outsider 7-6, 6-3 as he tried a new serve and volley approach he hopes can win him his first Grand Slam title.
"My goal is to win against the best players in the world," Tsonga said.
"To beat these guys you need to have something different. They all have: Rafa runs a lot, plays with a lot of spin, Roger takes the ball early, Novak too. Andy Murray is an incredible defender and his passing shots are just amazing.
"You need something different to be the best player on court and I think my way is to be really offensive, to play my serve and also volley too."
Fourth seed Monfils overcame Benjamin Becker 7-5, 4-6, 7-5 in a marathon encounter.
The lanky Frenchman, who has slipped to 16th in the world from seventh in September, squandered two match points before overcoming the German.
Monfils took nine attempts to bag the first set, eventually winning it with an audacious curling lob.