Former US Open champion Juan Martin del Potro on Wednesday paid tribute to fellow Argentine David Nalbandian after the one-time top-three player announced his retirement from tennis due to injury. \"Everyone knows Nalbandian was a really great player -- he won so may good tournaments,\" world number seven del Potro told reporters in Tokyo, after reaching the quarter-finals of the Japan Open. \"We have lost a really talented player from the tour.\" Nalbandian, perhaps best known for a stirring five-set comeback victory against Roger Federer in the 2005 Tennis Masters Cup final, hung up his racquet because of a persistent right shoulder problem. The gritty 31-year-old, winner of 11 ATP Tour titles, had slipped to 231st in the world rankings after another injury-hit season. \"On his day he could beat anyone,\" del Potro said of Nalbandian, who also reached the 2002 Wimbledon final where he lost to Lleyton Hewitt. \"I remember when he reached the final at Wimbledon,\" added the 25-year-old del Potro. \"I was very young at the time. There were also a lot of big Davis Cup wins and important matches he won, like when he beat Federer at the Masters Cup in Shanghai. Nalbandian had called the decision \"difficult\" when he made the announcement earlier. \"It is a sad day but my shoulder simply can\'t cope any more at the highest level,\" he said. He will play a final exhibition match against Rafa Nadal on November 23 in Buenos Aires. Nalbandian, who reached his career-high three in the world in 2006, also inspired Argentina to three Davis Cup finals, although they lost all of them. He once told French newspaper L\'Equipe a few years ago that he would also like to compete in the Rally World Championship. Nalbandian began the year in promising fashion, reaching the final in Sao Paulo where he lost to Nadal, but then his shoulder problem returned and an operation did not improve the situation. Source: AFP