That has been the Austrian's unfortunate fate four times in the previous six years, including in the past two French Open deciders.

Thiem has won just one of 13 sets in those four matches, although in fairness hardly anyone else has fared better against the king of clay at his favourite tournament, where he boasts a ridiculous win-loss record of 93-2 dating back to 2005.

The 2019 title match in Paris aside, Nadal has found the going much tougher at Melbourne Park, even in those years when he has arrived at the opening major of the year as world No.1, as is the case this time.

The fifth-seeded Thiem is in uncharted territory, through to the last eight at the Open for the first time in seven attempts following a straight-sets take-down of French showman Gael Monfils.

But at the age of 26 he realises the time to start challenging for trophies at all four of the slams is now.

"I'm not the youngest anymore, so I really have to be careful with my career now," he said.

"I have to really take the right decisions, and I'm also a little bit experienced already."

Were Nadal to go on and win a second Open title on Sunday, he would draw level with Roger Federer on 20 majors, which would make him a short-priced favourite to take outright ownership of the record with a 13th French Open crown in June.

But after ending the challenge of local hero Nick Kyrgios in four high-quality sets in the round of 16 on Monday night, he's looking no further ahead than the challenge posed by Thiem.

"I expect a very tough match," said the 33-year-old Nadal.

"He's playing well.

"I saw him play against Gael and he was playing a very high level of tennis.

"We know each other well.

"He's a player that I like a lot, the way that he works, the way that he plays, and the way that he tries his best always.

"It's a match that's going to be a tough one, but it will be interesting."

The winner will advance to a semi against German No.7 seed Alexander Zverev or three-time major winner Stan Wawrinka from Switzerland.

Australian Associated Press