VIENNA -- Alexander Zverev won't be able to mark his ascent to the top of the tennis rankings with another title after he was upset by Alex de Minaur in the semifinals of the Erste Bank Open on Saturday.

De Minaur won 6-4, 1-6, 7-6 (4) after surging into an early 3-0 lead in the decisive tiebreak for a win which strengthens his chances of qualifying for the season-ending ATP Finals next month.

Zverev will replace Jannik Sinner as the No. 1 player on Monday. The German will be the 30th different player to lead the rankings and the oldest first-time No. 1 since 1974 at 29.

De Minaur will face Carlos Alcaraz in the final on Sunday after the Spaniard won 6-4, 7-6 (2) against Daniil Medvedev in the other semifinal.