Serena Williams had to battle through a combative opening set lasting for well over an hour before blunting the upset ambitions of American Kristie Ahn 7-6(2), 6-0 on Monday to start her run at the French Open.
The 39-year-old Williams who is on her continuing quest of a record 24 Grand Slam singles titles, but has been stuck on 23 for three seasons.
Williams, the sixth seed and a three-time Paris champion, was given a test in the first set by Stanford graduate Ahn, whose family insisted she graduate from university before heading onto the WTA,
The No. 102 making her Roland Garros debut was beaten by Williams nearly a month ago at the US Open in the first round.
Williams is bidding for a 13th career trophy on clay,
She came from a break down twice in the opening set, but was able to take charge in the ensuing tiebreaker.
The second set was more comfortable for the veteran who ran out a 5-0 lead but was unable to convert on three straight match points on her own serve.
Williams finally got the job done on her fifth chance of the game with an ace.