Nicholas Newlife was so blown away by the 21-year-old Federer's brilliance in winning Wimbledon for the first time in 2003 that he went out and put a vast bet on the Swiss superstar to tie Pete Sampras's record of seven titles.
The Oxfordshire man placed a £1,500 bet at odds of 66/1 with bookmaker William Hill - but sadly he died three years ago before getting the chance to see his prediction come true.
Newlife's loss was charity's gain, however: when the high-rolling punter died in 2009, he left all his belongings to anti-poverty charity Oxfam - and among them were his long-range betting slips.
"Nick Newlife was a keen gambler on sports, and in particular a great tennis fan ... but sadly he did not live to see Roger land perhaps the most spectacular bet we have ever taken on tennis," said William Hill spokesperson Graham Sharpe.
The payout of £101,840 is the first of its kind in 40 years, and the charity says the money could feed 10,000 families in famine-hit West Africa for an entire month.
"All of Oxfam have been cheering Federer's progress for the past couple of weeks. The real hero, though, must be Mr Newlife, for his generous gift and his tremendous sporting acumen," said Oxfam marketing chief Andrew Barton.
It's not the first time that the charity has benefited from Newlife's betting: one of his other bequests to Oxfam was another betting slip which netted the charity £16,750 in 2009, when Federer won his 14th Grand Slam title.