Serena Williams' reign as the world's no.1 female player in the world is being threatened by Maria Sharapova, whose victory at the Brisbane International put her within striking distance of the American.

The 27-year old Sharapova opened her 2015 campaign with a bang after winning the Brisbane International last week. The Russian tennis superstar had a dominant showing through the first three rounds before grinding out a 7-6, 6-3, 6-3 win over Ana Ivanovic in the finals.

After missing her chance in reclaiming the top spot of the WTA World Ranking at the end of 2014, Sharapova seems very determined to get the top-ranking around her belt as she's now just 681 points behind Williams in the current standings.

On the other hand, Williams started her campaign a bit shaky after losing two of his three matches at a lesser competitive Hopman Cup in Perth. Serena has already amassed 18 Grand Slam titles in her career, and is now targeting no.19 at the Australian Open, where she last won five years ago.    

"Maria has won the event in Brisbane playing amazing tennis. The Russian Beauty is now just 681 points below Serena Williams that is also coming from a below par performance in Perth (Hopman Cup) where she lost 2 matches of 3 (and she was even bagelled twice). This gap means that if Maria wins the Australian Open she will be the world no.1," according to Singaporean tennis site Tennis Tonic.

For Sharapova to win back the world's no.1 title, she has to capture her second Australian Open title against a very competitive field consists of Williams, Victoria Azarenka and other up-and-coming stars.

Serbian star Ana Ivanovic also made a big jump in the ranking, moving past Agnieszka Radwanska of Poland and Genie Bouchard of Canada for the no.5 spot in the rankings.