Australia's former world number one Lleyton Hewitt has hired compatriot Tony Roche as his new coach.
Roche's split with world No 1 Federer took the tennis world by surprise
Roche split with Roger Federer before this year's French Open and has also worked with Pat Rafter and Ivan Lendl.
Hewitt, 26, currently ranked 21st, said: "Rochey and I have had a great relationship over the years.
"He's very positive and obviously one of the best coaches in the world. We both know what we need to do to get to the top of the game again."
Roche, who won the 1966 French Open and shared 12 Grand Slam men's doubles titles with John Newcombe, believes Hewitt still has what it takes to regain the ATP's top ranking.
"That's the goal... I think we've got to shoot for the top," said the 62-year-old who will first help Hewitt prepare for next month's US Open.
"I wouldn't be doing this job if I didn't think Lleyton had a chance of winning a Grand Slam."
Hewitt spent two years atop the ATP world rankings in 2001 and 2002, winning both Wimbledon and the US Open during that time.
But he has been unable to add a third major title in the years since.
Roche said winning the Australian Open would be the "real big goal" and believes Hewitt only needs to make minor changes to his game.
"I just think (he needs) a little bit more variety," he said. "Not so predictable, a little bit more aggressive. Also we'll be doing a lot of work on the serve."
Hewitt first worked with Roche as a teenager in the Davis Cup.