Australia's John Millman has sent defending champion Lucas Pouille crashing out of the Hungarian Open and march into the quarter-finals in Budapest.

The Queenslander prevailed 6-3 6-4 against the world No.14 for the biggest win of his career by ranking position.

Millman, who sits 80 places below the Frenchman, needed just 73 minutes to chalk up the victory on clay and set up up a quarter-final against Germany's Yannick Maden.

"I'm really happy with how I played, how I stuck with it mentally... I took my chances well today," Millman said.

"I've come close a few times of late but couldn't quite get through, so a really good result, especially considering it's my first tournament on clay in a long time."

The 28-year-old's win set up a quarter-final against Germany's Yannick Maden who overcame compatriot Maximilian Marterer 6-1 6-3.

Fourth-seeded Canadian Denis Shapovalov also suffered an early exit as the 19-year-old was beaten 6-2 6-4 by Georgia's Nikoloz Basilashvili.

Andreas Seppi powered past Russia's Mikhail Youzhny 6-1 6-2 to reach the last eight.