Venus Williams is dreaming of yet another final against sister Serena but admits she still has work to do before reaching the Australian Open's showpiece.

On Sunday, Venus defeated German qualifier Mona Barthel 6-3 7-5 to reach the quarter-finals at Melbourne Park.

Venus hit 31 winners and converted four break points as the seven-time grand-slam champion progressed to the last eight of the season's opening major for a ninth occasion.

The 36-year-old, who has never won the Australian Open, is now on a collision course with sister and world number two Serena.

"That could hopefully happen [playing Serena in the final]," she told reporters. "We both still have to work very hard to get there.

"I played a qualifier, and she hardly ever missed. So it doesn't matter who you come up against, they are coming and they want to win too. They have nothing to lose.

"I'm going to be focused on winning one round at a time and focus on doing what it takes to be there."

Venus, who has won five Wimbledon crowns and two US Open titles, is yet to drop a set in Melbourne.

It is the first time Venus has advanced to the quarter-finals of a grand slam without losing a set since 2010.

"At this point of the tournament, you want to feel good and you want to feel like you're doing everything perfectly," she added.

"But really, at the end of the day, it's about walking to the net, shaking hands as the winner. However that happens, two sets or three sets, that's how I want to walk to the end, as a winner."