Looking back at former members of Federer's team, there have been several individuals that stand out.
A proprietary trader for Credit Suisse in his day job, Reto Staubli has been a longtime friend of Federer's and was a former national player in Switzerland.
Staubli met 14-year-old Federer in 1995. Back then, Staubli, who played at a club in Basel, was one of the best players in Switzerland, he says. 'Roger wanted to watch the elders play,' Staubli says. 'It was interesting for him to see good-level tennis.'
Since then, they have remained great friends.
When Federer was about to split with his coach, Peter Lungren, at the end of 2003, he called Staubli for some informal advice before the 2004 Australian Open.
Again, in the rain delay of the 2004 Wimbledon final, when Federer was down 2-4 in the third set against Andy Roddick, Federer asked Staubli for advice on how he should counter the American's thunderous serves.
After returning to Centre Court, Federer won in four sets.
Staubli used to accompany Federer to many tournaments, effectively acting in a coaching capacity; in 2004, he travelled to 10 tournaments, which was 'an amazing experience'.
In recent times Staubli has curtailed his travel due to work commitments, but he still occasionally uses his vacation time to attend the bigger tennis events, such as Miami and the U.S. Open.
He has also been present at the Davidoff Swiss Indoors in Basel, Federer's hometown.
He remains a great personal friend. In September 2008, after Federer's 5th consecutive US Open win, the player and his then-girlfriend, Mirka, attended Staubli's wedding on the island of Majorca.
'Reto is a great friend,' Federer says, 'and has been extremely helpful to me during the most difficult times in my career.'