Paris:
Top seed and defending champion Roger Federer showed no mercy for best friend Stanislas Wawrinka on Sunday when he handed his Olympic gold medal-winning teammate a 6-3, 7-6 (7/5), 6-2 French Open thumping.
World number one Federer nows faces either Robin Soderling, the Swedish fifth seed who he defeated in the final last year, or Croatian 10th seed Marin Cilic for a place in the semi-finals.
The great Swiss has never lost to either man in 13 meetings.
On Sunday, Federer was barely troubled by his compatriot, easing to a fifth career win in six clashes in five minutes short of two hours.
Federer has reached the quarter-finals without losing a set, and is widely expected once again to be facing Rafael Nadal in the final next weekend, but he was refusing to get carried away by his smooth progress.
"I could have lost a set against Alejandro Falla in the second round and today against Stan and after this, you never know," said Federer.
"So I am happy with what's happened. I'm playing well, serving well and moving well. I hope it continues like this."
Wawrinka, who teamed up with Federer to win 2008 Olympic gold in Beijing in what he described as the the greatest night of his life, was broken in the third and ninth games of the opening set.
The 25-year-old achieved his first break of the contest in the opening game of the second, before Federer levelled in the eighth.
Wawrinka, bidding to reach a first Grand Slam quarter-final, got to 5-5 in the tie-break, but a terrible backhand volley was dumped in the net with Federer out of position.
That gave Federer set point and he was handed the second set when a dispirited Wawrinka netted again with a second service return.
Former Roland Garros junior champion Wawrinka angrily destroyed his racquet in the Paris dirt out of sheer frustration and picked up a code violation for his troubles.
His afternoon went steadily downhill, with Federer quickly stretching to a 5-1 lead in the third set on his way to another comprehensive victory.
Later on Sunday, British fourth seed Andy Murray faces Czech 15th seed Tomas Berdych for a place in the last four.
Eighth-seeded Jo-Wilfried Tsonga, the last French player still in the singles competition, takes on Russian 11th seed Mikhail Youzhny.