Li, the 2011 Australian Open finalist, broke her opponent four times in the match, hitting 21 winners to just six for Karatantcheva. Li established herself early in each set as she went through in one hour and 18 minutes to set up a match against Olga Govorstova of Belarus, who came from behind to defeat France's Pauline Parmentier 2-6, 6-3, 6-2.
"The more important thing is that I pass the first round. So I can think about the second round," Li was quoted as saying by Xinhua.
The quick victory doesn't make Li pleased with herself.
"I don't think I did as well as in Shenzhen," said Li.
"I felt many times that I could have scored but Karatantcheva saved it back. Maybe the ball was a little bit heavier."
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The sixth seed had a strong start to the year, winning the Shenzhen Open and reaching the semifinals of Sydney International last week.
The 2011 French Open winner lost to Kim Clijsters in the fourth round here last year after holding four match points in the second set tie-break.