Top seed Victoria Azarenka encountered no problems as she defeated Maria Jose Martinez Sanchez of Spain in the second round of the women's Olympic singles on Tuesday.

The Belarusian, who was celebrating her 23rd birthday, was in ferocious form in the opening set as three service breaks gave her a 6-1 win.

The second got off to a bad start for the world number one with a drop of serve but it mattered little as she closed out the match 6-2.

Azarenka's next opponent is Russian 16th seed Nadia Petrova, who beat Anna Tatishvili of Georgia earlier on Tuesday.