Veteran Venus Williams hailed her impressive three-set win over world number six and 2014 semi-finalist Agnieszka Radwanska.

Williams - the 18th seed - produced the goods at Melbourne Park on Monday, defeating Radwanska 6-3 2-6 6-1 for a spot in the Australian Open quarter-finals for the first time in five years.

The 34-year-old has rolled back the years in this campaign, having struggled for form and fitness in grand slams since being diagnosed with Sjogren's Syndrome in 2011.

But Williams is returning to the sort of form that saw her win seven grand slam titles and she is determined to continue her stellar run in Melbourne.

"I want to be playing deep in all my events. Everybody wants that," said Williams, who will face fellow American Madison Keys for a spot in the semi-finals.

"Now is my moment and I want to keep this moment going all year and then next year too.

"I think I played well when it mattered. Her style of game was completely different than the first three players I played.

"The first three players I played tried to blast me off the court. This was the first time there was any sort of rhythm at all.

"The way she hits the ball is so different. A lot of times, especially for a player like me, you feel like, wow, why am I not hitting more winners?

"That's not just always the answer. It's definitely a balance between being aggressive and being patient and being smart because the way she plays is very deceptive. Not everyone plays that way."

Radwanska, who failed to make it past the fourth round for the first time since 2010, simply had no answer at the crucial moments of the match.

"She was playing very well, very solid from the back, very good serve as well," the Pole said.

"She was very consistent. Returning very well. I was putting first serve pretty much all the time and everything was going back. She really had answer for everything."