The Spaniard's record reign at the clay-court tournament finally ended Sunday as he lost 6-2, 7-6 (1) to top-ranked Novak Djokovic in the final.
Nadal won his 46 previous matches and the last eight titles at Monte Carlo — beating Djokovic in last year's final — and his last defeat here was against Guillermo Coria 10 years ago. Nadal missed the 2004 tournament through injury before winning his first Monte Carlo title the following year.
Nadal then beat Roger Federer in the next three finals. His eight straight titles were an ATP record for one tournament.
"I cannot be happier than I am in this moment knowing what I've been through the whole week, actually two weeks," said Djokovic, who twisted his ankle two weeks ago playing for Serbia against the United States. "If somebody told me 10 days ago I'd be winning the trophy, I wouldn't think it's so realistic, to be honest."
Djokovic faced Nadal for the 16th time in a championship decider, and they are now 8-8 in finals. The Spaniard had won the previous three, including the French Open final last year.
"I think he played a little bit better than me, especially in the first set," Nadal said. "I felt that I was playing really well the second set and I was having more chances than him."
Djokovic sensed Nadal was there for the taking.
"I knew after yesterday's match that I had a feeling that I had a big chance to win against Rafa if I was on the top of my game," Djokovic said. "The first six, seven games, eight games, were unbelievable. It's the best that I can play on clay."
Nadal looked set to take the match to a third set after opening up a 4-2 lead in the second, but his serve let him down. Especially in the 12th game, when Djokovic broke him to love to take the momentum back heading into the tiebreaker.
"When I was 6-5 down, I think out of next 10, 15 points, I lost only one. So that's an unbelievable effort at that stage," Djokovic said. "Analyzing the game and the matches that I had against him in the past on different surfaces, I know if I can play on that level for long period of time, I have a very good chance of winning."
Nadal has reached five consecutive finals since returning from a knee injury in February — winning three, and losing two — while Australian Open champion Djokovic won his third title of the year and 37th overall.
But Nadal still feels he is some way short of full fitness.
"I need a little bit more physical performance," he said. "That's the real thing, to play all those points with the same intensity."
Djokovic sealed the victory on his first match point with another booming forehand winner.
After a brief shower, the match started with a delay of around 45 minutes, and the Serb raced ahead 5-0 in just 25 minutes. Neither player has won a set 6-0 against the other in 34 meetings, but Djokovic came very close before Nadal summoned up the strength to save five break points in the sixth game.
Djokovic won the first game easily, concluding it with an ace; Nadal then dropped serve by returning wide.
It was as a sign of things to come in a first set in which Djokovic hit 14 winners to Nadal's seven and made almost half as many unforced errors.
After 25 minutes of brutally effective shot making by Djokovic the unthinkable started to look very possible: that Nadal could lose a set on clay 6-0.
French Open winners Roger Federer and Gaston Gaudio, and French Open runner-up Guillermo Coria, have managed it, and Djokovic came very close. But Nadal dug deep, winning one mammoth point that spanned 27 shots, and landing crucial serves.
Nadal held before moving ahead for the first time, breaking Djokovic and holding for 4-2. Then, after Djokovic had dropped his serve again in the 11th game, Nadal had a chance to level the match on his serve.
Instead, he crumbled, and he looked despondent in the tiebreaker.
Their finals have gone in cycles: Nadal won the first five; Djokovic the next seven; Nadal the following three.
With the French Open five weeks away, Djokovic has chosen a good time to buck the latest cycle.
"Of course, I want to win Roland Garros," Nadal said. "That's no secret. But I need to keep on having the right positive mindset."