The world No 3 was beaten in three sets by fellow Spaniard Fernando Verdasco who reached the last 16 in Florida with a 6-4 2-6 6-3 victory.
For Verdasco, the world No 34, it was only his second triumph over Nadal in 15 meetings.
But despite the surprise loss the 28-year-old, 14-time Grand Slam winner remains upbeat saying: ???I’m going to fix it. I don’t know if in one week, in six months, or in one year, but I’m going to do it.
“I need to fix again the nerves, the self control on court. It’s not a tough issue to fix. I’m going to keep trying. I’ve been under control during, let’s say, 90 per cent of my matches.
“I’m practicing with the right attitude. I’m arriving in an important part of the season for me. I didn’t want to arrive to that part of the season with that loss today, obviously, but that part of the season will arrive.”
Verdasco said of his win: “Obviously, always beating a player like Rafa is one of the biggest victories that you can have in tennis.
“It’s always really nice to play in an almost packed stadium against one of the best players in history.
???I tried to keep calm and be aggressive but of course at the same time you cannot be too aggressive. It was very windy, and many times you need to adjust.”