Carlos Alcaraz says he was made to feel like a "13-year-old" by Grigor Dimitrov after being beaten in the quarter-finals of the Miami Open.
Bulgarian Dimitrov won 6-2 6-4 to set up a last-four meeting with Germany's fourth seed Alexander Zverev.
"He played amazing tennis, almost perfect," said top seed Alcaraz, 20.
He was aiming to become the first man to win the 'Sunshine Double' - back-to-back titles at Indian Wells and Miami - since Roger Federer in 2017. But 11th seed Dimitrov upset the Spaniard and Alcaraz added: "I couldn't find solutions. I couldn't find a way to make him feel uncomfortable on the court. It was a great game from his side.
Dimitrov dominated the opening set, breaking Alcaraz's first service game before striking again at 5-2.
The two-time Grand Slam champion fought back from 4-1 down in the second, but Dimitrov broke for a fourth time to wrap up a second successive win over the Spaniard in 92 minutes.
"To win against him, you have to play at your best - that's just how it is," said Dimitrov, who also beat Alcaraz at October's Shanghai Masters.
"Sometimes simplicity is genius. It's very hard to do it, especially when you play against an opponent like that, but I was able to dictate the game, read the game a bit better than the last time."
Dimitrov will return will return to the top 10 for the first time since 2018 if he beats Zverev to reach the Miami final.
CAPTION: Azarenka won the Miami title in 2009, 2011 and 2016
Meabwhile, Victoria Azarenka continued her bid for a fourth Miami Open title with victory over Yulia Putintseva to set up a semi-final encounter with Elena Rybakina.
The Belarusian 27th seed, who won her last title at the event in 2016, needed almost three hours to claim a 7-6 (7-4) 1-6 6-3 win against Putintseva.
Fourth seed Rybakina beat Greek eighth seed Maria Sakkari 7-5 6-7 (4-7) 6-4.
On the other side of the draw, American Danielle Collins beat French 23rd seed Caroline Garcia 6-3 6-2 on Wednesday.
Former Australian Open runner-up Collins, 30, is planning to retire from the WTA Tour at the end of the season.