Serena Williams has survived a tough early test

World No.1 and defending champion, Serena Williams has survived a tough early test to safely advance to the second round of the Australian Open at Melbourne Park.

Serena Williams of the United States celebrates after beating Camila Giorgi of Italy during their first round match at the Australian Open tennis championships in Melbourne, Australia, Monday, Jan. 18, 2016.(AP Photo/Vincent Thian) Source: AP

The six-time champion needed one hour 45 minutes to see off Italian Camila Giorgi 6-4 7-5 in sweltering conditions on day one of the tournament.

A knee injury had prevented Williams from completing a competitive match since the U-S Open in September, but the American came through unscathed to book a second-round meeting on Wednesday with either Latvian Jelena Ostapenko or Taiwan's Su-Wei Hsieh.

Williams told Channel Seven she was pleased to have been given such a good test in her first match at the Australian Open.

She said, "Yeah, it wasn't very easy. She obviously plays really well and she knows how to hit the shots. And I haven't oplayed a competitive match in a really long time, but I think it was really good for me to come out here and get through it. And it wasn't quick, so that actually worked to my advantage as well."