Rublev won 29 of 39 first-serve points (74.4 percent) and tallied three aces to get past Thiem, who was playing on a protected ranking. Rublev cruised through both sets and never trailed during the match.
In the day's other semifinal match, American Sebastian Korda beat Arthur Rinderknech of France 7-6 (2), 6-3. Korda smashed eight aces, won 34 of 41 points on the first serve (82.9 percent) and racked up 29 winners to Rinderknech's 16.
With the win, Korda was able to advance to his first final this year.
UniCredit Firenze Open
No. 1 seed Felix Auger-Aliassime of Canada had no problem ousting third-seeded Lorenzo Musetti, picking up a 6-2, 6-3 victory to advance to the final at Florence, Italy.
Auger-Aliassime picked up eight aces and 21 winners against Musetti, who was playing in front of his home fans. The Canadian also won 29 of 36 first-serve points (80.1 percent) while taking advantage of seven unforced errors from Musetti.
J.J. Wolf is set to face Auger-Aliassime in the final after defeating Swedish qualifier Mikael Ymer.
Wolf slammed home nine aces against just one double fault and finished with 25 winners.
