Juan Martin del Potro says his straight-sets victory over Novak Djokovic in the first round of the Olympic Games tournament restored belief in his ability.
The Argentine - US Open champion in 2009 - had been a major player on the ATP Tour prior to a series of wrist injuries that robbed him of two years of competition.
Del Potro made his long-awaited return in February and recorded victories over Dominic Thiem and Grigor Dimitrov in Madrid and Wimbledon respectively, but it was not until his outing in Rio that the confidence began to return.
He received possibly the toughest opening-round draw in Brazil against the then world number one Djokovic, who had completed a career grand slam earlier in the year at Roland Garros.
The odds were upset, though, as the 28-year-old powered his way past the Serbian 7-6 (7-4) 7-6 (7-2), causing a major shock that started Djokovic's slip from the top of the men's game.
On the flip side, Del Potro charged to the final - where he lost to Andy Murray - and used the momentum to reach the US Open last eight and guide Argentina to Davis Cup glory, and he credits that Djokovic win for his impressive end to 2016.
"Since that moment I started to feel good inside the court and enjoying after a long time," he is quoted as saying by Ole.
"Also I realised that with a good preparation I would be able to fight against the best in the world.
"The court was full, but there were many Argentinians and the people made me feel that I could still fight against the best ones.
"Something awoke within myself and I started to believe that I could achieve it."
Del Potro may have to wait to compete against the best in 2017, though, after confirming he is a major doubt for next month's Australian Open.