Paris: No-one knows the importance of a killer instinct in tennis more than Roger Federer, but even the Swiss maestro accepts it will be tough to keep his feelings in check when he faces great friend Stanislas Wawrinka on Sunday.
The Olympic doubles champions and practice partners face each other across the net for the first time in a grand slam, and with Wawrinka boasting a rare clay victory over the world number one Federer knows he faces a formidable foe.
"We know it`s going to be a tough match, so I`m very happy about this challenge, because he`s a great player. I`ll have to play great tennis, also," the top seed said after swatting aside German qualifier Julian Reister 6-4, 6-0, 6-4 on Friday.
Federer has throughout his career been something of a mentor for Wawrinka, at 25 three years his junior, offering him advice in the early stages of their friendship.
Yet Wawrinka, who won doubles gold alongside Federer for Switzerland in Beijing two years ago, scored a three-set win on clay in Monte Carlo last year and will likewise forget their friendship for what promises to be a captivating fourth-round battle.
"I`m not his coach, but at the beginning it`s like giving tips and advice. I saw him growing, and he had many problems with the indoors before on the hard or quick surfaces.”
"I saw how he developed on these surfaces. It`s always very interesting to see how he can continue and make progress. He`s no longer asking for tips, which is a good sign."
Like Federer, the softly spoken Wawrinka has yet to lose a set in his current Roland Garros campaign, and has reached the last 16 for the first time in Paris.
"I`ve never played against him during a grand slam, so that`s a bit of a difference," Federer said. "He`s really fit, and we have the same physical trainer. We know what we do."
Wawrinka needed no reminding of the influence Federer had had on his career.
"When I was young and I arrived on the tour, he was already top 10. Because of him, I have a gold medal in my house, so I`m very happy for that," said Wawrinka after dispatching Italian Fabio Fognini in straight sets on Friday.
"It`s never easy because he`s really a good friend. We know each other so well, so it`s never easy to play him, especially here in French Open.”
"But then when you go on court you try to do your job."