James Blake said the nightmare events of 2004 had given him the inner strength and determination to upset world No. 2 Rafael Nadal at the Masters Cup.
Blake broke his neck, lost his father to cancer and developed shingles two years ago, but said he had emerged stronger from his troubles.
The US player was the last to qualify for the season-ending tournament but stunned Nadal in straight sets late on Monday.
"I definitely think I'm stronger from everything that happened in 2004," Blake said after the match.
"I don't think I would have won this match today, I don't think I would have won a lot of matches, and I don't think I would be the person I am if all that happened to me didn't happen to me in 2004," he said.
Blake injured himself running into a net-post while practising in Rome that year, before his father succumbed to stomach cancer in July.
He also developed shingles that paralyzed half his face and blurred his vision, putting his tennis future in doubt.
The 26-year-old from New York also suffers from a curved spine and wore a back-brace for five years as a teenager.
Blake has enjoyed a sensational year, winning five titles and breaking in to the top 10 for the first time.
But he faced an anxious wait to have his Masters Cup place confirmed after a third-round defeat last week in Paris.
"I'm the guy that's supposed to be the easy match in this tournament. But I'm just happy to be here," he said.
"I was definitely nervous, I was biting my nails," he added.
Blake ditched his studies at the prestigious Harvard University in favor of tennis but says he does not regret his choice and will complete his education when he stops playing.
"I had a lot of fun out there today. This is my job, so to have fun at your job is pretty rare," he said.
"Also, to make whatever I made today, about US$120,000 in a day's work, even for a Harvard grad that's not easy," Blake said.
He is hopeful of an extended playing career after turning professional at a relatively mature 19.
"I feel a little younger in tennis years than some of the other guys because I lost a whole year in 2004 and I didn't start until late," he said.
"It seems like guys get more burnt out or their bodies give out just from the grind of the travel, so I don't feel like I'm as old as my age really says," he added.
Blake will also face Nikolay Davydenko and Tommy Robredo in Gold Group in the round-robin stage of the US$4.45 million tournament.
The world's two top players, Roger Federer and arch rival Rafael Nadal, will face off next week in South Korea in an exhibition game, organizers said yesterday.
"Federer and Nadal are scheduled to arrive at Incheon International Airport on Monday aboard their private jets," Lee Seung-hwan, chief of Sema Sports Marketing, which is organising the event, told Yonhap news agency.
All reserved seating for the showdown, which will take place on Nov. 21 on a hardcourt in Seoul, has been snapped up.
Nadal is responsible for four of Federer's five defeats this year but has suffered a slump in form since losing the Wimbledon final to the Swiss.
Nine-time Grand Slam champion Federer is already assured of ending his third straight season as the top-ranked player and is closing on Jimmy Connors' record of 160 weeks at number one.
Sema Sports has hosted similar exhibition matches before, including a showdown between Venus Williams and Maria Sharapova last year.