Taylor Fritz has snapped Rafael Nadal's 20-match winning streak as the Californian claimed his first ATP Masters 1000 title at Indian Wells.
There were errors from both throughout as Fritz took the first set and the pair entered a tiebreaker at the end of the second, with neither having lost one at Indian Wells this year in singles.
But it was the 24-year-old, ranked 20th, who emerged victorious to finish 6-3 7-6 (5) over the world number four, with Fritz becoming the first American to win the tournament since Andre Agassi in 2001.
Nadal however was left concerned by a breathing problem after the defeat.
The 35-year-old's run this season had seen him claim three titles including a 21st grand slam crown at the Australian Open, and he was the favourite to win the first Masters event in 2022.
The Spaniard had battled through several close matches to reach the final and needed treatment at the end of his semi-final against Carlos Alcaraz on Saturday.
It was clear from the start of Sunday's final that all was not well, with Nadal declining to chase down balls, rubbing his chest and losing the first four games.
He went off court at the end of the first set with the doctor but decided to carry on and had his chances in the second despite his struggles.
Nadal will prioritise finding out what the problem is, saying: "When I'm breathing, when I’m moving, it’s like a needle all the time inside. I get dizzy a little bit because it’s painful. It’s a kind of pain that limits me a lot. It’s not only about pain, I don’t feel very well because it affects my breathing."
Nadal had already decided not to play in the Miami Open over the next fortnight and will instead have a short break before the clay-court season begins next month.
He said of his first defeat of the year: "I wanted to make it perfect before clay. It has been very, very, very beautiful. Honestly I am sad because of the way I was not able to compete. It’s tough to have these feelings, every day, but in the final it’s very, very ugly.
"But I am not the kind of person that goes down or goes very high emotionally depending on the moment. I am normally stable, putting everything in perspective.
"Of course, the last two months have been amazing, unforgettable, very emotional. I enjoyed things that I never thought I could live again a few months ago.
"Now is the moment to try to solve this problem as soon as possible, try to start on clay. The thing that worries me is about what’s going on there, what I have to do now to recover and how long it’s going to take."
Earlier, Poland’s Iga Swiatek won the women’s title with a commanding victory over Maria Sakkari.
Swiatek rose to number two in the world after a 6-4 6-1 win over her Greek opponent.
"We’ve already started a pretty cool rivalry and I think it’s going to last a few more years so it’s pretty exciting," Swiatek said in her on-court interview.
"We’re going to play many more finals. Today was pretty crazy because of the conditions. My team did an amazing job."
