Germany’s Angelique Kerber became the first women’s top seed to lose in the opening round of the French Open with defeat by Ekaterina Makarova.
The top seed went down 6-2 6-2 in one hour and 22 minutes, leaving her number one status in the balance.
Both Simona Halep and Karolina Pliskova have the chance to take top spot for the first time with good runs in Paris.
However, Halep is recovering from injury and Pliskova fell in the first round last year, symptomatic of the uncertainty in the women’s draw that led Halep to claim up to 15 players are in with a chance of the title.
Kerber, a first-round loser last year as well, barely figured among the favourites on the eve of the tournament.
Although her defeat might have been a shock in terms of rankings, with Russia’s Makarova at number 40 in the WTA standings, it was no great surprise.
The 29-year-old from Bremen has been struggling for form this year, reaching just one final and winning only three matches on clay heading into Roland Garros.
Kerber only regained the number one ranking from Serena Williams after the American stepped away from the tour as she awaits the birth of her first child.
While Kerber fully merited that status last year, when she won the Australian and US Opens, the German arrived in Paris ranked 13th for the year so far.
The superb footwork, tenacity from the baseline and all-round aggressive defence that took her so far in 2016 have deserted her in 2017.
That has left her old frailties exposed, with a weak serve broken six times by Makarova on Philippe Chatrier Court.
After falling 5-1 down on her way to losing the first set, Kerber rallied late in the second, but the clinical edge has also gone from her game.
A final tally of just two break points converted from 16 illustrated that lack of certainty in the key moments.
Makarova, 28, goes on to face Lesia Tsurenk or Kateryna Kozlova in round two, and will feel she has as good a chance as anyone to feature in the latter stages.