There was a big shock on day one at Wimbledon with Japan's Naomi Osaka crashing out with a first-round defeat to Kazakhstan's Yulia Putintseva.
The third meeting of the two women, the third victory for Putintseva, ended 7-6(4), 6-2.
The US Open and Australian Open champion was seeded second in the women's singles draw and followed 10th seed Aryna Sabalenka out the exit door.
The 21-year-old from Belarus lost to Magdalena Rybarikova in straight sets; 6-4, 6-2.
The 16th seed from the Czech Republic Marketa Vondrousova was also beaten in straight sets by American Madison Brengle.
Simona Halep, Karolina Pliskova, Anastasija Sevastova and Elina Svitolina were among the top seeds to win today and earn progression to the second round.
Men's sixth and seventh seeds exit Wimbledon
There were a couple of big names in the men's singles to go out this afternoon including the 6th seed Alexander Zverev and 7th seed Stefanos Tsitsipas.
The German 22-year-old lost by 3 sets to 1; 4-6, 6-3, 6-2, 7-5, against Jiri Vesely of the Czech Republic while Tsitsipas from Greece lost in 5 sets against Italian Thomas Fabbniano; 6-4, 3-6, 6-4, 6-7, 6-3.
Novak Djokovic had little trouble in reaching the second round as the defending champion started proceedings on Centre Court with a straight sets win over Germany's Philipp Kohlschreiber; 6-3, 7-5, 6-3.
The Serb admitted after the game though, that he wasn't happy with the start of his performance.
"The break in the first game wasn't the start that I was looking for," commented Djokovic after the win. "But I think I came with the right intensity. I answered back really well.
"From that moment onwards I played a pretty good match I thought. It was good quality, I held my serve well."
Djokovic will face 26-year-old American Denis Kudla in the next round.
Among the top seeds joining Djokovic in the next round are Gael Monfils, Daniil Medvedev, Stan Wawrinka, Milos Raonic and last year's runner-up Kevin Anderson, who all recorded wins today.
