Jannik Sinner has become the fourth teenager to reach a Miami Open men's final, after Andre Agassi, Novak Djokovic and Rafael Nadal.
Stefanos Tsitsipas led 2-0 in the second after winning the first set but bowed out to 26th seed Hubert Hurkacz at the Miami Open.
Daniil Medvedev's woes against Roberto Bautista Agut continued on Wednesday as Jannik Sinner moved through to the semis.
Top seed Daniil Medvedev was too good for Frances Tiafoe, while Stefanos Tsitsipas is in the hunt for his first ATP Masters title.
Stefanos Tsitsipas and Andrey Rublev reached the last 16, however, in-form seed Aslan Karatsev farewelled Miami.
Daniil Medvedev could barely walk but still progressed from the third round on Sunday.
Greek star Stefanos Tsitsipas and Kei Nishikori will meet in the third round of the Miami Open.
Last week's Mexican Open champion Alexander Zverev went down in the second round in Miami to Finland's Emil Ruusuvuori.
Lorenzo Musetti reached last week's Mexican Open semi-finals and started at the Miami Open with victory.
Vasek Pospisil took aim at the ATP chairman as he lost in three sets to Mackenzie McDonald in Miami.