PARIS, France - Former World No.1 Serena Williams began her quest for a 24th Grand Slam title with a victory at Roland Garros, surviving a topsy-turvy opening set to ultimately ease past fellow American Kristie Ahn, 7-6(2), 6-0.

"The biggest difference was just confidence," Serena summed up after the match. "I just need to play with more confidence, like I'm Serena.

"So that was it. I just started playing like that, and I love the clay and I started playing like it, opening the court and moving and sliding."

The 23-time Grand Slam champion, who withdrew from the Internazionali BNL d'Italia due to an Achilles injury sustained during the US Open semifinals, twice trailed her countrywoman by a break in the opening set, only to catch fire in the tie-break and ride that momentum to a one hour and 41 minute victory on Court Philippe-Chatrier.

"I do think her level dropped a little bit in the beginning of the first set and I took advantage of that. I think her level was so high in the first set that I just needed to lift my level more than what I did."

Williams played Ahn for the first time just two weeks ago, kicking off her US Open campaign with a tense two-set win in the first round.

Ahn, who upset former French Open champions Svetlana Kuznetsova and Jelena Ostapenko to reach the fourth round in Flushing Meadows last year, led by early breaks in both sets against Williams a fortnight ago, and was at similar intensity to start their clay court clash on Monday.

"I have put so much perfectionism into my habits that if it's not perfect, then it's not enough for me. That is something I have been working on.

"I was able to get over that in the recent past couple of months, really, just since the restart from COVID. I feel like that has been what I needed to just deal with, just understand that my level of greatness is sometimes crazy high and a win is a win."

Navigating an epic nine-deuce game, the unseeded 28-year-old converted her sixth break point and soon moved ahead 4-2.

Serena battled back in inimitable fashion, drawing Ahn into a marathon game on her own serve before leveling the set at four games apiece, converting her sixth break point opportunity with a fearsome backhand winner.

Though Ahn shook off the lost momentum to break serve at love, Williams struck a searing forehand return to take a 0-40 lead of her own as her countrywoman served for the set. 

Holding at love as the match hit the one-hour mark, the former World No.1 nabbed the first mini-break of the ensuing tie-break, taking a 4-2 lead at the change of ends thanks to a deftly angled backhand and a missed forehand from Ahn.

"I have to let go of that expectations. That doesn't mean I'm lowering my expectations. It just means I'm having realistic expectations of not winning every point, every game, every shot.

"It sounds crazy, but, you know, that's me and that's what makes me me. I'm me. I'm Serena. At some point I'm always going to have some level of perfection, but I just need to have a more reasonable level so I cannot put so much stress on me mentally."

Williams, who reached the US Open semifinals just two weeks ago, ended a 22-shot rally with a forehand winner and soon clinched the Sudden Death with her seventh ace.

The three-time French Open champion took that momentum and ran with it, racing ahead 5-0 as she cleaned up her stats sheet in spectacular fashion and broke serve three times in a row.

Ahn made an impressive last stand as she reversed a 40-0 deficit in the final game to save four match points, but Williams made no mistake on her fifth, striking her 11th ace to end the contest.

In all, Williams hit 26 winners to 36 errors (28 of which came in the first set) and converted five of 14 break point opportunities while saving six of eight faced on her own serve. Ahn acquitted herself well throughout, but will ultimately rue missed chances in that opening set, ending the match with 27 errors to 13 winners. 

Up next for Serena is fellow mom and US Open quarterfinalist Tsvetana Pironkova, who ousted 2015 semifinalist Andrea Petkovic in straight sets as a wildcard earlier in the day. The pair played in New York two weeks ago, where the Bulgarian led by a set before Williams edged through in three.

"She's playing well, but I am too. I'm ready to play her. She'll be ready to play me. It will be a long match, she will get a lot of balls back, but so am I. I'll be ready."

2020 Roland Garros Highlights: Serena shakes off Ahn to advance