Australian wildcard Alex Bolt caused a major upset at the Adelaide International, winning his way into a first ATP quarterfinal.

South Australian Bolt toppled German No.7 seed Jan-Lennard Struff 6-3 6-4 in a second-round boilover at Memorial Drive.

World No.157 Bolt took control early against Struff, ranked 120 places higher than the local, and never relinquished.

Bolt secures a quarterfinal berth againstFelix Auger-Aliassime, who overcame Australia’s James Duckworth 6-3 7-6(0).

Rublev, on three hours’ sleep, advanced to the quarter-finals with a comprehensive 6-3 6-3 second-round win against American Sam Querrey.

The world No.18 arrived in Adelaide after winning last week in Doha – his third ATP title.

But while hoping his upward curve extends deep into the Australian Open, starting Monday in Melbourne, the 22-year-old reckons he’s still well shy of joining elite company.

“It’s (an) amazing feeling to be top 20 for the first time,” said Rublev, who will meet Brit Dan Evans in the quarterfinals. “There are still so many things that I can improve.”

American Tommy Paul trounced Uruguay’s Pablo Cuevas 6-1 6-2 to book a quarterfinal against Spaniard Albert Ramos-Vinolas, who accounted for his compatriot Jaume Munar 7-6(3) 6-3.

Spain’s Pablo Carreno Busta downed Frenchman Jeremy Chardy 6-3 6-2 to set up a last-eight meeting with South African qualifier Lloyd Harris, who upset Serbian Laslo Djere 7-6(5) 6-3.