Angelique Kerber became the first women's top seed in the Open era to lose in the opening round of the French Open on Sunday.
The German has been badly out of form in 2017, despite sitting at the top of the rankings, and the only surprise about her 6-2 6-2 loss to Ekaterina Makarova was the magnitude of it.
Russian Makarova, ranked 40, won five of the first six games and, although she came under more pressure in the second set, she kept Kerber at arm's length.
The top seed dropped serve six times and made 25 unforced errors in a match that lasted an hour and 22 minutes.
Makarova, who has made the fourth round here twice, was a tough opponent for a player who does not like clay and has reached just one WTA Tour final all year.
Kerber won the Australian Open and US Open titles last year and reached the Wimbledon final.
The German, who also lost in round one last year, has had a miserable season and is not a fan of clay so the result came as no real surprise.
She said: "This year, the expectations are much bigger, especially in the big tournaments and the grand slams. And the expectations are also from me really big because I know what I can do, what I did last year.
"But right now I think that I have to find to myself again and just try to forget the clay court season as soon as possible, and then reset and start from the grass courts again."
Earlier, two-time Wimbledon champion Petra Kvitova marked her comeback after spending five months on the sidelines following a stabbing by an intruder in her home with a straight sets victory over Julia Boserup.
Venus Williams is a possible title contender a month before her 37th birthday and the 10th seed survived a close match against China's Wang Qiang.
Wang was a break up in the second set but could not force a decider, with Williams winning 6-4 7-6 (7/3).
The American made her debut at Roland Garros 20 years ago, reaching her only final in 2002, which she lost to sister Serena.
Eighth seed Svetlana Kuznetsova defeated Christina McHale 7-5 6-4 to reach round two, but Australian Open semi-finalist Mirjana Lucic-Baroni was upset 6-3 6-3 by Turkey's Cagla Buyukakcay and 15-year-old American Amanda Anisimova was beaten on her grand slam debut, losing 3-6 7-5 6-4 to Kurumi Nara.
Defending champion Garbine Muguruza opens proceedings on day two on Philippe Chatrier against another former winner, Italian Francesca Schiavone.
Second seed Karolina Pliskova faces Zheng Saisai of China while French hope Kristina Mladenovic meets Jennifer Brady.
