Argentina’s David Nalbandian beat Nicolas Massu of Chile 7-6 (7-0), 6-1 to end the defending champion's quest for another shock Olympic title.
The seventh-seeded Nalbandian improved to 3-1 against Massu in their first meeting for four years.
Massu turned the tennis world on its head in Athens 2004 when he became the only men's player to win both singles and doubles titles at the same Games in the modern era.
Dmitry Tursunov and Mikhail Youzhny had already ended his bid for a doubles repeat with partner Fernando Gonzalez.
Now 28, and ranked a lowly 125 in the world, Massu needed an invitation from the International Tennis Federation (ITF) to compete here.
Chinese shuttlers shocked
British veterans Gail Emms and Nathan Robertson won a three-game thriller on Tuesday against China's champions to clinch a place in the quarterfinals of the Olympic badminton mixed doubles.
The Athens silver medallists produced a gritty comeback against China's second seeds Gao Ling and Zheng Bo after giving up a one game lead to win 21-16, 16-21, 21-19.
With a capacity crowd roaring for China, the British pair appeared rattled in the second game, and were down 12-17 in the third, before winning seven points in a row as they finally edged in front for victory.
Lifter Liao joins China’s gold rush
Liao Hui of China won the men's 69kg weightlifting at the Beijing Olympics here on Tuesday to give the hosts their 11th gold medal of the Games.
He hoisted 158kg in the snatch and 190kg in the clean and jerk for a total of 348kg. Liao was made to sweat in the closing moments as Vencelas Dabaya-Tientcheu of France, made an audacious play for the gold.