A fired-up Serena Williams sent out a warning to the young pretenders of women's tennis when she powered to a crushing 6-1 6-3 victory over world number one Victoria Azarenka to win the Madrid Open on Sunday.

The 30-year-old former number one, seeded ninth at the premier clay event in the Spanish capital, made the most of Azarenka's nervous start on the blue dirt of the Manolo Santana show court to race into a 4-0 lead.

After breaking the Belarussian's serve for a third time to clinch the first set, Williams turned the screw with another break early in the second and clinched victory on her first match point when Azarenka completely missed an attempted return.

It was the American's second title of the year after her success on the clay at Charleston last month and her 41st singles crown overall, putting her in joint 13th on the all-time list with Belgian Kim Clijsters.

Azarenka, who flung her racket to the floor in frustration on the way to being broken in the second game of the second set, had beaten Williams just once in seven previous meetings and was bidding to improve on her runners-up finish in 2011.

It was only her third defeat in a year in which the 22-year-old won her first grand slam singles title at the Australian Open, which lifted her to the top of the rankings, and has earned more than $4 million in prize money.

Williams clubbed 26 winners to Azarenka's six and smashed down 14 aces, while her opponent did not manage a single one and offered up six double faults.