Defending champion Roger Federer suffered a shock 6-3, 7-5 defeat by Frenchman Julien Benneteau, who has yet to lift a tour title during his 13-year career, in the World Indoor Tournament quarterfinals on Friday.
The top seed was broken three times in the opening set. Benneteau, 31, broke again early in the second set before the world number two, backed by a capacity crowd of 10,500, broke back.
Federer had chances to break again in the 11th game but world number 39 Benneteau managed to hold him off before clinching victory on his first match point as a backhand pass from the Swiss went out. Benneteau next meets fellow countryman Gilles Simon who put out Martin Klizan when the Slovakian retired through injury while trailing 6-7, 6-3, 3-0. Juan Martin Del Potro swept aside Finn Jarkko Nieminen 6-3, 6-4 and will play Grigor Dimitrov in the last four after the Bulgarian came from behind to defeat Cypriot Marcos Baghdatis 6-7, 7-6, 6-3 in a thriller.
Oldie Williams on top
Serena Williams showed tennis was not just the domain of teenagers as she climbed back to the top of the world rankings on Friday, becoming the oldest female to hold the coveted position at the age of 31.
The American is world number one for the sixth time in her storied career after finishing off former Wimbledon champion Petra Kvitova 3-6, 6-3, 7-5 in the quarterfinals of the Qatar Open in Doha.
Williams will meet Russian Maria Sharapova in the semis. The Russian brushed aside Australia's Samantha Stosur 6-2, 6-4. Victoria Azarenka of Belarus, who saw off Italian Sara Errani 6-2, 6-2, will face Agnieszka Radwanska in the semifinals. Radwanska beat Caroline Wozniacki 6-2, 7-5.
Results (Brazil Open, Quarterfinals, prefix denotes seedings): 1-Rafael Nadal (Esp) bt Carlos Berlocq (Arg) 3-6, 6-4, 6-4; David Nalbandian (Arg) bt 2-Nicolas Almagro (Esp) 7-6 (7-5), 3-6, 7-6 (7-3); Martin Alund (Arg) bt Filippo Volandri (Ita) 7-5, 7-6 (7-5); Simone Bolelli (Ita) bt A Montanes (Esp) 6-4, 6-4.