Serena Williams celebrates 100 weeks as world No 1

Serena Williams celebrated her 100th consecutive week as world No 1 by taking a step closer to another milestone in the Australian Open.

Williams joined Martina Navratilova and Chris Evert on 18 grand slam titles with her US Open victory last year and a 19th would take her within three of the record held by Steffi Graf.

The top seed will face far tougher challenges than that posed by Belgian world number 106 Alison Van Uytvanck as the tournament progresses, but she was nevertheless delighted to secure a 6-0 6-4 win on Margaret Court Arena.

'I always have first-round jitters and nerves but it's good to come out here and win today,' said Williams, whose current spell at the top of the rankings started on February 18, 2013.

'It's in the back of my mind (a 19th title) but at the same time there are so many other players who want to win this tournament as well.

'If I could get to 19 in Australia that would be beyond amazing. I have a lot of work to do but I am just going to enjoy myself.'

Williams' sister Venus also had no problems in reaching the second round, the 18th seed defeating Spain's Maria Torro-Flor 6-2 6-2.

Wimbledon champion Petra Kvitova, sixth seed Agnieszka Radwanska and eighth seed Caroline Wozniacki all eased into the second round without dropping a set, but Wozniacki in particular will face a far tougher task in the last 64.

Wozniacki will take on two-time winner Victoria Azarenka on Thursday after the Belarusian, who is unseeded after a miserable 2014 on and off the court, defeated American Sloane Stephens 6-3 6-2.

'Being an unseeded player it's not a surprise that I have a tough draw or tough opponents in the early round,' Azarenka said. 'I just need to go through that. I accept the challenges.