Like most Australian tennis players, Alex de Minaur does not naturally feel at home on the red clay of the European Mediterranean swing.

But the 25-year-old Sydneysider has not reached No.11 in the world without working hard on all aspects of his game and has gradually becoming accustomed to the unfamiliar ochre.

The Australian No.1 demonstrated his growing confidence on the surface with a battling three-hour win at the Foro Italico over the in-form Canadian Felix Auger-Aliassime. That took him into the last 16 in Rome for the second time in six attempts.

De Minaur recovered from after the disappointment of losing the first-set tie-break to win 6-7 (2-7) 6-4 6-4, his 25th victory of the season.

He let a 3-1 lead slip in the deciding set but broke again in the ninth, then served out to seal his first victory against last week's Madrid finalist.

"I think Felix is a very good player on the clay," said de Minaur. "He had a lot of confidence coming in, so I'm very happy how I stayed in the match at all stages. I was positive, no matter what came my way. I could have had a double break in the third to maybe secure the match. I didn't get it, ended up getting broken, and I managed to compose myself so I'm very happy with that."

It was de Minaur's second win against a Top 20 opponent on clay in 13 attempts.

"[My results on clay] aren't great, so plenty of room for improvement," said de Minaur. "Every time I'm out here I'm enjoying it, with a proper mindset, and I think I can play well. Especially when you have nice hot conditions. I'm taking it a match at a time. I'm happy with a quality win on the clay today, and we move on."

Awaiting de Minaur in the fourth round on Tuesday evening (Wednesday AEST) will be sixth seed Stefanos Tsitspas. The Greek defeated Briton Cameron Norrie 6-2 7-6 (7-1) and has lost two of 14 claycourt matches this season.

The winner will play either Chile's Nicolas Jarry or France's Alexandre Muller, who stunned Andrey Rublev 3-6, 6-3, 6-2.

Rublev had won seven straight matches on clay having been champion in Madrid and Muller admitted of his first win over a top-10 opponent: "It's amazing. I didn't expect to win against Andrey. I knew I had my chance, but it is special to win against a Top 10 player. I'm very happy."

There were also wins on Monday for Hubert Hurkacz and Tommy Paul while Sebastian Baez upset 10th-seed Holger Rune 2-6 6-2 6-3.