Nadal was handed his fifth loss on clay this season when he was beaten 6-7 (7-9), 2-6 by Wawrinka.
Nadal, who recently dropped out of the top five on the ATP rankings for the first time in a decade, admitted that he offbeat during the match and added that Wawrinka was absolutely unstoppable as he "hit amazing shots".
"I didn’t have enough leg in some moments today," Nadal said after the match. "He played crazy. He hit amazing shots in a lot of moments, and especially important ones. At 6-2 he played a lot of good points.
"I am not very happy with the way I played. During the night the ball is bigger, the bounces are not that high. So he has the chance to go for it. And he was on fire."
With the French Open just around the corner, Nadal knows that he has to shrug off his struggles as of late and regain his title as the 'King of Clay'.
While that will be easier said than done, Nadal has vowed to be more competitive during the French Open, which he has won nine times in the last 10 years.
However, the world number seven also pointed out that "life continues" if he fails to capture his 10th French Open title.
"I am ready to accept the challenge," the Spaniard said. "If I go to Roland Garros (and) I lose (and) I don’t play well, life continues. It’s not the end of the world. I won so many times there. I don’t want to (win) 15 Roland Garros. That’s for sure. It’s normal that I can lose. Losing is part of life. I am sure that I can be competitive."