Australian Open finalist Andy Murray has been forced to defend the behaviour of his fiancee Kim Sears after she served up a volley of expletives at her partner’s opponent.

Sears’ rant came during a tense first set, which Murray lost, before going on to win the second set 6-0 and close out the match in four sets.

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Video footage of the bizarre behaviour has become an instant hit online, with viewers engaging in a game of ‘guess the swear words’.

“@BenRothenberg: Forget how big the diamond is; THIS is what true love is made of. #ausopen https://t.co/jETjH7CunD” f****** hilarious!

— Anne Keothavong (@annekeothavong) January 29, 2015

Due to a lack of sound, the footage doesn’t reveal the precisely what Sears said, but guesses from amateur lip readers include “f***ing have that you flashy Czech, you flashy f***” and “f***ing have that Czech you fat old f***”.

Whatever was said, Murray didn’t seem concerned.

“In the heat of the moment, you can say stuff that you regret,” he said.

“When there’s a lot of tension surrounding something … it’s completely normal that the whole first set everyone was tight.”

“Even Tomas, who very rarely says anything on the court … there was tension there for him as well,” he said.

Far from alienating fans, Sears’ courtside temper tantrum has catapulted her to legend status among some tennis-lovers.

“Kim Sears moves past Mirka Federer in the WAG power heckle rankings,” social media user Ton Skeel said.

For sports broadcaster ESPN, it was the engagement rings of the mens’ fiancees that were the focus of the match.

While Murray and Berydch battled it out on the court, ESPN was busy comparing the value and size of Ms Sears and Berdych’s fiancee Ester Satorova’s rings.

Both couples are newly engaged.

Keep it classy, @ESPNTennis! Love the engagement ring comparison during this dramatic #Murray/#Berdych match #AusOpen pic.twitter.com/HmKmIfTBex

— Matt Whitfield (@lifeontheMlist) January 29, 2015

According to tennis commentator Rennae Stubbs, Ms Sears wasn’t impressed when she saw herself and Ms Satorova on a split screen, allegedly saying “Oh for f***’s sake”.

Twitter users slammed the broadcaster over its focus on the jewellery, telling them to “keep it classy” and asking why people needed to know the value of the women’s rings.

Channel Seven also zeroed in on the fiancees, placing footage of both of them reacting on a split screen.

Murray will play in the Australian Open final on Sunday night, taking on either reigning champion Stan Wawrinka or world number one Novak Djokovic.

Classic comment out of #KimSears mouth when they showed her & Berdych Fiancé on a split screen. “Oh for F… Sake”!! Gotta love Kim!

— rennae stubbs (@rennaestubbs) January 29, 2015