Roger Federer will play the French Open and Wimbledon without a coach after splitting with Tony Roche, the world number one said on Monday.
Federer, who had worked with the 61-year-old Australian on a part-time basis since 2005, blamed communication problems for the parting of ways, which he announced on Saturday after a run of four tournaments without a title.
"It wasn't an easy decision," Federer told reporters at the Hamburg Masters, where he is the top seed.
"He's helped me a lot but in the end he was a part-time coach. We were together only 15 weeks a year and I just thought the communication wasn't going very far any more."
Federer, who said he had been thinking about a change for some time, added that he has the experience to go into the next two Grand Slam tournaments without help.
"I'm not going to take a coach because I know what it takes to win," he said. "I don't want anyone interfering with my preparation."
Federer won six of his 10 Grand Slams while working with Roche, who had previously coached Ivan Lendl and Pat Rafter.
But the 25-year-old Federer has had success on his own, too. He won his first Grand Slam at Wimbledon in 2003 with Peter Lundgren but let the Swede go less than six months later. He then went on to lift three more majors in 2004 after opting to go it alone.
Federer, who has never won the French Open, needs to take the Roland Garros title to become only the third man after American Don Budge and Australian Rod Laver to hold all four majors at the same time.
Spain's Rafael Nadal, the second seed in Hamburg, has won the French Open for the last two years and is on a 77-match winning streak on clay, dating back to April 2005.
Federer and Nadal are among the top seeds with a first-round bye in Hamburg.