Ash Barty puts Nick Kyrgios to shame with 'crazy' comeback

Just a few hours after Nick Kyrgios gave Aussie tennis a black eye with his ‘disgusting’ tantrum at the Cincinnati Masters, Ash Barty went some way to restoring our reputation.

Barty produced an extraordinary comeback to continue her quest to regain the World No.1 ranking, beating Anett Kontaveit in the fourth round after the Estonian served for the match.

Barty rallied from a set down and was staring at defeat down 4-5 in the third, but managed to survive to book her place in the quarter-finals.

The top-seeded Australian clinched a battling victory with a deep forehand winner and raised her right fist in triumph after outlasting Kontaveit in two hours and 10 minutes.

In the process, Barty struck 31 winners and nine aces, breaking Kontaveit six times.

French Open champion Barty, currently ranked second, can reclaim the world top spot by reaching the tournament final in the US Open warm-up event in Ohio.

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Into the last eight in Cincinnati for the first time, Barty, who fought past Maria Sharapova in her opener, will play Greece's Maria Sakkari after she dispatched Aryna Sabalenka, 6-7 (7-4) 6-4 6-4 to advance.

"The best thing is when my back was against the wall, the tennis was there," Barty said.

"It may not have been there the whole match, but we were able to find it when we needed it."

Barty puts Kyrgios to shame

Barty’s remarkable comeback came around the same time as Kyrgios was being handed the biggest fine on ATP record.

Kyrgios has been hit with a $US113,000 ($A167,000) sanction and also faces a possible suspension for verbally abusing and spitting towards the chair umpire during his second-round defeat to Karen Khachanov on Thursday.

The fine is the largest total fine since 1990, the start of the ATP World Tour’s official record books, according to Tennis.com.

The fines included five charges of unsportsmanlike conduct totalling $US85,000, $US20,000 for verbal abuse, $US5,000 for audible obscenity and $US3,000 for leaving the court without permission.

The ATP said they are further investigating whether a suspension is warranted.

"The ATP is looking further into what happened during and immediately after the match to see if additional action is warranted under the Player Major Offense section of the code. That could result in an additional fine and/or suspension," the game's governing body said.

The 24-year-old Australian won the opening set against his Russian opponent, despite foot and ankle issues, before unleashing a profanity-laced tirade at umpire Fergus Murphy, throwing his towel over a camera and forcing broadcasters of the US event to switch to an overhead view.

Kyrgios took umbrage with Murphy, who he has previous history with, over his monitoring of the shot clock and berated the Irishman for most of the match.

He became obsessed with the issue, repeatedly calling Murphy a "potato" and labelling him a "disgrace" and the "worst ref in the world".

Murphy eventually responded by handing Kyrgios a point violation after Khachanov won the second-set tiebreaker to level the match, when the Canberran overstepped the mark by screaming out an obscenity.

Kyrgios then followed this up by asking for a toilet break. He took two racquets with him and smashed them in the players' tunnel before returning to the court.

After a double-fault handed Khachanov the match and the players shook hands, Kyrgios told Murphy "you're a f***ing tool bro" and appeared to spit in the direction of the umpire before he shunned the traditional handshake.

with AAP