Cilic confident in Melbourne after stunning Rublev to reach Last 16

Croatia's Marin Cilic celebrates victory against Russia's Andrey Rublev (AFP/MICHAEL ERREY)

Former Australian Open finalist Marin Cilic said he felt "really good" about his tennis and was confident of making an impact after reaching the second week at Melbourne Park.

The experienced Croat, the 2014 US Open champion, had one of his great Saturday nights at a Grand Slam with a four-set demolition of Russian fifth seed Andrey Rublev to reach the Australian Open last 16 for the eight time.

It was a superb display of clean hitting from the big-serving Cilic, who pushed Roger Federer all the way before losing an epic 2018 Australian Open final in the fifth set.

The 27th seed left world number six Rublev ruefully shaking his head at times as the Croat smacked 55 winners.

Cilic beat Rafael Nadal in the 2018 quarter-finals on his way to the final and reckoned he can make another deep run this year.

"When my game is there, I feel really confident," said the vastly experienced Cilic.

"I feel that my game is actually there. I'm playing really good."

The 33-year-old won his 19th and 20th ATP Tour titles last year at Stuttgart and St Petersburg -- his first since 2018 as he worked his way back inside the world's top 30.

"I have great experience in the Grand Slam level here in Australia," added the former world number three.

"I played amazing in 2018. Was just a bit unlucky in 2019 with my knee injury.

"I feel that I'm playing well, I can challenge these guys. But still, I have to take it match by match and put my head down and keep going the same way I did in these last three matches."

The 33-year-old will face Canada's ninth seed Felix Auger-Aliassime on Monday for a place in the quarter-finals and he is wary of the big-hitting Canadian.

"I'm expecting absolutely another difficult challenge ahead," said Cilic.

"Felix has started the season very well. Canada won the ATP Cup and I saw he played incredibly well against Dan Evans."

Cilic believes the match will come down to who can hold their nerve and play the critical points best.

"He's a big hitter, has big serve, big forehand. On my own side as well as the net I'm doing quite similar things," he said.

"So it's going to come down to who is going to be better at those critical points."