Nishikori dumped out in Paris
The French Open witnessed its first shock on Monday afternoon as ninth seed Kei Nishikori was beaten in straight sets by Martin Klizan.
The Japanese player is one of the rising stars of the game and already has two titles to his name this season.
That looked set to become three when he led Rafael Nadal by a set and a break in the final of the Madrid Open earlier this month.
But a back injury eventually forced him to retire in the third set and Nishikori's presence at Roland Garros had been in doubt after he pulled out of the Rome masters.
He told Japanese reporters he would not have come to Paris for any other tournament than a grand slam and he cut a forlorn figure in his 7-6 (7/4) 6-1 6-2 defeat by Slovakian Klizan.
Nishikori insisted it was a lack of practice rather than any lingering effects of the injury that had cost him.
He said: "It was the first time playing points after Madrid, so I didn't have much rhythm. And also my serve, I didn't hit any serve 100 per cent before today.
"I thought it was going to get better, I would get more rhythm after a couple sets, but I couldn't. So I couldn't do anything today.
"I was playing well on clay in Europe, so it's very sad for me to lose first round here. But it's good I didn't have another injury."
Injuries are nothing new for Nishikori, the first Japanese man ever to be ranked in the top 10.
"It really sucks," he said. "Especially in Madrid, I won the first set, and I had to kind of let go of the match.
"It's tough for me, but I guess this is my tennis life. I have to take care of my body and injury will come again, for sure. So I have to mentally be ready.
"I have to do whatever I can do to get healthy."
Marin Cilic had a much better time of it, the 25th seed winning the first nine games of his 6-0 6-3 7-6 (8/6) victory over Pablo Andujar.