Russia's Maria Sharapova blows a kiss to the spectators after defeating Belgium's Kim Clijsters

Russia's Maria Sharapova blows a kiss to the spectators after defeating Belgium's Kim Clijsters Roger Federer fought through the longest three-set singles match in the Open era Friday when he beat Argentina’s Juan Martin del Potro 3-6, 7-6 (7/5), 19-17 to reach the Olympic final. Wimbledon champion Federer was on the brink of a shock defeat on Centre Court after dropping the first set, but the world number one finally subdued del Potro after a marathon four hours and 26 minutes.
The match, 23 minutes longer than Rafael Nadal and Novak Djokovic’s Madrid semi-final in 2009, comes after Jo-Wilfried Tsonga took 66 games to beat Milos Raonic in the second round — the most seen in an Olympic three-setter.
The great escape means Federer, 30, is guaranteed at least a silver medal. In Sunday’s final, he will face world number two Novak Djokovic or Britain’s Andy Murray.
After a relatively barren two years by his standards, Federer is suddenly enjoying another of his dominant periods and this hard-fought victory showed his hunger for success remains as strong as ever. Less than a month ago, Federer, a doubles gold-medallist with Stanislas Wawrinka in Beijing four years ago, was crowned Wimbledon champion for a record-equalling seventh time.
Now he is just one win away from completing the ‘golden slam’ of titles in all four majors and the Olympic singles gold.
Meanwhile, Maria Sharapova swept into her first Olympic final as the Russian world number-three defeated compatriot Maria Kirilenko 6-2, 6-3 in the semi-finals on Friday.
The 25-year-old will play Serena Williams, who routed world number one Victoria Azarenka 6-1, 6-2.
Serena, who hit 33 winners and 16 aces, is now guaranteed at least a silver medal.