Fourth seed Cilic dug deep to seal a 6-4, 2-6, 6-3 win over the in-form Paul, who had won 12 of his past 14 matches coming into today’s contest.

Third seed Khachanov, who was runner-up at the Adelaide International 1 event, suffered a 7-6(7), 7-5 defeat by world No 58 Rinderknech.

In the other quarterfinals, Thanasi Kokkinakis is due to play Aleksandar Vukic in an all-Australian clash, while Brazil’s Thiago Monteiro will take on French qualifier Corentin Moutet.

In the women’s event, third seed Coco Gauff reached the last four with a 6-3, 6-4 victory over Croatia’s Ana Konjuh but American Madison Brengle was forced to retire from her match against Alison Riske due to a slight calf injury.

Brengle retired from the match with the score 3-3 in the first set, sending Riske through to the semifinals.

Fourth seed Tamara Zidansek of Slovenia is due to face Lauren Davis later today, while Madison Keys is up against eighth seed Ludmilla Samsonova.