Melbourne- As seed after seed in the women's draw fell on the opening day of the Australian Open on Monday, world number two Maria Sharapova was vowing that she would not be one of them.

Eight women's seeds departed on Monday, with world number five Ana Ivanovic the most prominent, before Sharapova restored some order to the rankings with a 6-4 6-1 victory over Petra Martic in the day's final match on Rod Laver Arena.

"There were quite a few upsets today and of course I was very well aware of that," Sharapova said after her victory that ruined Martic's 24th birthday. "I certainly didn't want to be one of them."

Sharapova, who had entered the season-opening grand slam having won the Brisbane International title earlier this month, appeared comfortable against Martic but did run hot and cold throughout the first set, taking a 5-2 lead only for the Croatian to battle back to 5-4.

In the second, the five-times grand slam champion faced some staunch resistance and while she took a 5-0 lead, the scoreline did not reflect the closeness of the match.

Sharapova, however, as was evident through much of the match, was able to convert the crucial points when they mattered and sealed it with her sixth ace.

"I played an opponent that's capable of playing very good tennis," Sharapova said of the 184th-ranked Martic. "She's been injured a little bit I believe in the last year or so, but she can play. She's got some big weapons.

"For a first round against someone that's already played a few matches, I knew I had to be really strong from the beginning (because)... you never know what you're going to get.

"You get really inspired opponents that are not seeded in the first round that are either coming from qualifying, and everyone's eager to do well in this type of environment.

"You can't ever underestimate their potential and how they can play. They're going to fight till the very last point."