Although Kerber - a two-time grand slam champion in 2016 - arrived at Roland Garros as world number one, expectations for the German were low given her struggles for form this year.

Nevertheless, the manner of her defeat on Court Philippe Chatrier was alarming to say the least.

Makarova dictated play for the bulk of the match and overcame an apparent bout of nerves late on, which saw her twice drop serve with the winning line in sight only to immediately restore her two-break advantage.

The world number 40, Makarova represented one of the toughest opponents Kerber could have drawn in round one and wasted little time in stamping her authority on the contest.

A break for the Russian in the first game of the match set the tone for a one-sided opening set, and Kerber cut a despondent figure as she quickly slumped 3-0 down in the next.

To her credit, Kerber refused to go down without a fight, but her subsequent rally only delayed the inevitable as Makarova came through a lengthy final game to prevail.

As a result, Kerber retains the unwanted record of having won just one match against an opponent in the top 30 all season and her position at the summit of the rankings is increasingly vulnerable.

Makarova will face Lesia Tsurenko or Kateryna Kozlova in round two, with the exit of the top seed adding further intrigue to a draw that was already viewed as wide open with Serena Williams absent.