Johanna Konta faces the toughest task in tennis to beat Serena Williams - but she may have a secret weapon.

Konta's new coach Wim Fissette has guided all four of his previous charges to victories over Williams, and claims he knows how to make the Briton his fifth.

Under Fissette, Kim Clijsters ousted Williams en route to winning the US Open in 2009, Sabine Lisicki beat her at Wimbledon in 2013, Simona Halep conceded just two games when she won at the WTA Championships in 2014 and last year, Victoria Azarenka overcame the American in the final at Indian Wells.

Now, it is Konta, from Eastbourne, hoping to upset the 22-time major champion at the Australian Open, where both are yet to drop a set so far and the reward is a spot in the last four.

''I feel very happy I can say I have beaten Serena with four different players,'' Fissette said.

''And the most important thing is to really make my players feel they can beat her, that she is not unbeatable, because she is not.

''She is the best player ever, there is no doubt about that. But you can beat her.

''It's a fact that too many players go on court thinking Serena is unbeatable, but I'm telling you very clearly, she is not.''

Williams is the most decorated player currently playing the game but Konta is the one in form as she chases her tenth consecutive victory and fifth in six against opponents in the top ten.

The challenge against Williams, however, is to play the player rather than the success.

After losing to the 35-year-old in the third round here, Nicole Gibbs said: ''I have literally been watching her for the entirety of my tennis life - I think that does play into how you feel on the court. It becomes more than a tennis match.''

Fissette, however, is not worried about Konta feeling intimidated.

''It is tough, of course. She is the toughest opponent out there but I don't see Jo going into a match not believing she can win it,'' Fissette said.

''She will have respect, of course, lots of respect, but I don't see her going into the match like Gibbs and saying Serena is like unbeatable.

''I saw this mentality in Jo when she first came on the WTA Tour. That is what I found most interesting about her. I saw that she believed she could beat anyone.''

Konta is likely to go on the offensive against Williams given her strengths lie in her pinpoint serve, destructive backhand and eagerness to dictate rallies from the baseline.

Fissette explained how he first noticed Konta when scouting her for a match against Azarenka in 2015. He said he struggled to find any weaknesses.

''My first memory was when Azarenka played her in Wuhan - that was when I first had to do some research on Jo,'' Fissette said.

''And actually I found it difficult to analyse her game because she has a lot of weapons but I could not find really any weaknesses in her game.

''I also remember her going on court. She had come from nowhere to playing someone like Azarenka and her attitude was, 'I'm here to beat you. I respect you but I'm here to beat you'.''