Serena Williams overcame a challenging first set to beat Kristie Ahn 7-6 (7-2) 6-0 and progress into the second round of the French Open.
The 23-time Grand Slam champion, playing in her first match on clay this season, found the going tough in the first set as she battled with her serve and surprisingly notched up 28 unforced errors.
Williams turned it on when she needed to in the tie-break, and then used her frustration to hold her fellow American, who she also beat in the first round of the US Open earlier this month, to love in the second set.
She will face another one of her US Open opponents in the second round, Tsvetana Pironkova, after the Bulgarian beat Andrea Petkovic 6-3 6-3.
Williams, who like many other players was wrapped up with a number of layers, took less than a minute to secure her opening service game.
However, that was not indicative of the road ahead and, instead of flying through on serve, she found herself being continually tested and pushed.
Of the two Americans, it was Ahn who was striking through the ball and using her power, while Williams missed the mark. The 39-year-old's regular unforced errors disrupted her flow and she converted just two of the eight break points she created.
With her wealth of experience, the three-time French Open champion was able to flick the switch in the tie-break, though, and duly turned the tables on her opponent.
Once Williams became the aggressor, the second set took just 27 minutes as she hit 11 winners and added four aces for good measure.
Petra Kvitova, the seventh seed, moved into the second round after a 6-3 7-5 win against Oceane Dodin.
The two-time Wimbledon champion, who missed last year's tournament due to injury, took just 76 minutes to secure her victory.
She anchored her game with a potent first serve, winning 86 per cent of points on it, and put down eight aces to Dodin's three. Kvitova will face Jasmine Paolini next, after the Italian beat Aliona Bolsova 6-4 6-3.
The fifth seed Kiki Bertens came back from a set down to beat Katarina Zavatska 2-6 6-2 6-0.
Bertens faced high-class tennis from her opponent in the first set, and made 19 unforced errors of her own, before she re-grouped.
In the second and third sets, she tidied up her game, while Zavatska's own error count increased. The result sets up a second-round clash between Bertens and Sara Errani.
Last year's runner-up Marketa Vondrousova will not be repeating her deep run this time around, as she was thrashed 6-1 6-2 by Iga Swiatek.
Another notable first-round casualty was the 2009 champion Svetlana Kuznetsova, who was beaten 6-1 2-6 6-1 by Anastasia Pavlyuchenkova.
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