The Latvian stunned the world last year with a series of upsets before beating Simona Halep in the final but struggled for any sort of rhythmn today against her Ukrainian opponent.

The 20-year-old was beaten 7-5, 6-3 in a match lasting little over 90 minutes.

It marked the first time a defending French Open women's singles champion has lost in the first round since Anastasia Myskina was beaten by unseeded María Sánchez Lorenzo in 2005.

Seven-time Grand Slam singles winner Venus Williams was also beaten today by China's world number 91 Wang Qiang.

Wang triumphed 6-4, 7-5 against the American, who was runner-up at Roland Garros in 2002.

Britain's Johanna Konta also crashed-out with a straight-sets defeat to Kazakhstan's Yulia Putintseva to continue her dismal French Open record.

Fourth seed Elina Svitolina of Ukraine was more successful in beating Australia's Ajla Tomljanovic 7-5, 6-3.

Germany's highly-rated Alexander Zverev was among winners in the men's singles draw today.

The second seed thrashed unseeded Lithuanian Ricardas Berankis 6-1, 6-1, 6-2 as he chases a first Grand Slam trophy.

French number one Lucas Pouille beat Daniil Medvedev of Russia 6-2, 6-3, 6-4 elsewhere, while Japan's Kei Nishikori earned a 7-6, 6-4, 6-3 win against another home player in Maxime Janvier.

Bulgarian Grigor Dimitrov won 6-1, 6-4, 7-6 against Egyptian lucky loser Mohamed Safwat, who was a late call-up to replace the injured Serbian Viktor Troicki,

Australian Nick Kyrgios was forced to withdraw before his scheduled match with fellow countryman Bernard Tomic as he proved unable to recover from his elbow injury.

Spain's Rafael Nadal is set to begin his pursuit of an 11th French Open men's singles title against Simone Bolelli of Italy tomorrow.