Opelka struggled with his last three Top 10 opponents, but revealed a higher level of play to topple the 10th-ranked Spaniard. Bautista Agut, who was looking to keep pace with Matteo Berrettini in the Race to London, has fallen further behind after the loss. Berrettini reached the semifinals in Vienna to increase his lead and can widen the gap this weekend.
Opelka, who also took out ATP Finals hopeful Fabio Fognini, will next face either Alex de Minaur or Jan-Lennard Struff in Saturday's semifinals. Opelka is looking to win his second title of the year after tasting victory at the New York Open.