Li Na began the defence of her French Open title with an easy win on Monday, defeating Romanian Sorana Cirstea 6-2 6-1 in 58 minutes.
China's Li, who became the first player from an Asian nation to take a grand slam singles title when she won at Roland Garros last year, was never challenged by the 43rd-ranked Cirstea.
In front of stands that were barely half-full on Philippe Chatrier Court, Li, who played with her right knee strapped up, allowed the Romanian few chances and few points.
Li said she was still upset about losing to Russian Maria Sharapova in a dramatic and rain-interrupted Italian Open final eight days ago.
"After that final I told everyone: 'Don't talk to me about tennis for three days'," the world number seven told a news conference.