Venue: Roland Garros, Paris Date: 23 May-6 June
Coverage: Live video streamed from 1000 BST on BBC Sport website (UK only) and BBC red button; commentary on BBC 5 live sports extra; also live on Eurosport; text commentary on BBC Sport website
Details of BBC coverage
Federer claimed his first French Open title with a win over Robin Soderling last year
Roger Federer has still to drop a set in his French Open defence after he saw off his close friend Stanislas Wawrinka 6-3 7-6 (7-5) 6-2 in the fourth round.
The top seed was barely troubled by his fellow Swiss as he cruised through the first set before taking a tie-break in the second as Wawrinka crumbled.
The match swiftly ran away from the 25-year-old as Federer remained on course for a fifth successive Paris final.
Federer will play Robin Soderling next after the Swede's win over Marin Cilic.
"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 won the pair's last meeting on clay at the Monte Carlo Masters in 2009, but never looked like overhauling his friend after losing a keenly fought second set.
Breaks in the third and ninth games had proved more than enough to see Federer to victory in the first, but Wawrinka grabbed his first break of the match in the opening game of the second.
It was an advantage that he clung to until Federer struck back in the eighth.
At 5-5 in the tie-break Wawrinka's hopes of a first Grand Slam quarter-final were still alive before two simple errors gifted Federer a decisive lead.
First, having manoeuvred Federer out of position, he netted a backhand volley before he then patted a second-serve return short on the next point.
His racquet bore the brunt of his frustration and he incurred a code violation for caving in the frame as he angrily beat it against the court floor.
Federer brought a merciful end to his misery as he wrapped up the third set in 27 minutes.
"Frustration. Nothing but frustration," said Wawrinka when asked about his outburst.
"In the second set I really felt I was dominating. I had taken the lead in the tie-break. I was playing well, and I lost myself because of two very stupid mistakes."
Soderling, who lost in last year's final to Federer, also made his way through to the last eight in straight sets as he beat Croatian 10th seed Cilic 6-4 6-4 6-2.
It was the pair's first meeting and had been widely expected to occupy the Court Suzanne Lenglen crowd for longer than one hour 41 minutes.
But Soderling's powerful groundstrokes overwhelmed his 21-year-old opponent and will give him hope of bucking a record of 12 losses from 12 matches against Federer.
"I think he's taken advantage of the better ranking he's had since the last year here," Federer said.
"I've never lost against him, so obviously that's a good record to have. But because of the improvements he's made, he's an opponent not to underestimate.
"He beat incredible players on the way to make the finals here last year, so clay seems to also become really his surface of preference, as well."
Jo-Wilfried Tsonga, France's last remaining player in the event, bowed out against 11th seed Mikhail Youzhny of Russia as a suspected hip injury forced his retirement after losing the first set 6-2.
"This event is too big, I wanted to give it all I have got. Nobody will blame me for fighting," said Tsonga.
Youzhny will be play his first Roland Garros quarter-final against the winner of Andy Murray and Tomas Berdych's fourth-round clash.