American will face Maria Sharapova in WTA Championships final but not before paying tribute to Polish player for her fitness.
Serena Williams awe for Agniezka Radwanska
Sharapova beat Victoria Azarenka 6-4, 6-2 in the second semi-final, a day after Azarenka had made sure of finishing the year as the top-ranked player. Sharapova will finish No 2 even if she beats Williams in tomorrow's final.
Williams was never challenged by the fourth-ranked Radwanska apart from dropping serve in the fourth game of the first set.
Radwanska spent more than eight hours on court in her previous three matches, while Williams required less than five to win her three round-robin matches. The difference showed, although Williams did not think that was the case at the start of the match. "I definitely had an idea that she was tired," Williams said.
To reach the semi-finals, Radwanska beat Sara Errani in a match that took 3 hours, 29 minutes - the longest best-of-three-sets match in WTA Championships history.
"I told her [after the match] it was awesome that she played so well and played through another match after playing a good eight hours," Williams said.
Sharapova, who rose to No 1 briefly after winning the French Open, clinched the match against Azarenka when she held to lead 5-1 in the second set after prevailing in a 15-minute game that went to nine deuces, the last one on a double-fault by Sharapova.
Azarenka, of Belarus, ended her best year on a losing note but she became the first woman to reach the US$7 million (Dh25.7m) mark in prize money for a year.
Meanwhile, Roger Federer and Juan Martin del Potro will meet tomorrow for the first time since their epic Olympic Games clash after both beat French opponents to reach the final of the Basel Open.
Argentine Del Potro overpowered Richard Gasquet 6-2, 6-2 to reach his fifth final of the year while world No 1 Federer met more resistance before beating Paul-Henri Mathieu 7-5, 6-4.
The top-seeded Spaniard David Ferrer reached the Valencia Open final for a third time, beating Ivan Dodig of Croatia 6-4, 6-7, 6-1 today.
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