Serena Williams insists she is playing with no pressure after sealing her place in the Australian Open final on Thursday.

The world number one was tested early by American countrywoman Madison Keys before coming out a 7-6 (7-5) 6-2 winner in their semi-final at Rod Laver Arena.

With 18 grand slam titles, Williams is among the sport's greats " tied fourth for most majors in the women's game.

But the 33-year-old, who will face Maria Sharapova in the final on Saturday, thinks the time has come for her just to have fun.

"I was so off [at the Hopman Cup before the Australian Open]," Williams said.

"I felt like I wasn't moving well. I just wasn't feeling great on the court. It's been so long since I've even been in a final here.

"I was kind of like, 'Oh, let me just try.'

"My theory now is to relax and play the match as best as I can.

"When I step on the court and hear the announcer, I don't have to win anymore. I can just relax and have fun."

Williams has battled a virus for the past week, but reported she is getting better every day.

She is targeting a strong start against Sharapova, over whom she holds an incredible 16-2 winning record.

"It's going to be important for me to get off to a good start, I think," Williams said.

"With that being said, if not, I'm going to be ready to fight. I think she really wants this. I can see that she wants to do well.

"She wants to improve her game. She wants to take it to the next level. So, you know, I have to know that she wants to win probably a lot."