DOHA, Feb. 15 (Xinhua) -- Serena Williams made the history at the age of 31 as the American became the oldest world number one after a quarter-final victory at the Qatar Open on Friday here.

Her 3-6, 6-3, 7-5 battle against Petra Kvitoa of the Czech Republic put her back to the No.1 seat two and a half years later.

American Chris Evert set the previous record of 30 years and 11 months in 1986, six months younger than Serena, whose career was also damaged by pulmonary embolism and a series of injuries.

"I am so sensitive nowadays. I am always crying, but I never thought I would be here again you know," said Williams.