Stockholm - Sweden's Robin Soderling finally announced his retirement on Wednesday, more than four years since his last match.
"I have realised that I will not be fit enough to play tennis at the level I demand of myself," said Soderling, 31, to the Swedish news agency TT.
Soderling fell ill with glandular fever in the summer of 2011, but he did not realise the seriousness of his sickness and continued to train, although he struggled physically.
He described his condition as "overtraining syndrome" and said in a press release that "with this disease it has been impossible for me to train 100 percent".
Soderling reached the final of the French Open in both 2009 and 2010, before rising to a career-high fourth in the world rankings in late 2010.
His greatest moment was perhaps inflicting on clay court king Rafael Nadal his first ever defeat at the French Open in 2009.
In fact, until the Spaniard lost to world No 1 Novak Djokovic in the Roland Garros quarter-finals earlier this year, that remained his only defeat on the Parisian clay in 71 matches.
"Although my career as a tennis player is over I still have a bright future ahead of me and my schedule for the next few years is full," said Soderling, who won 10 titles in his career.