Nick Kyrgios splashes the cash during shopping trip with Greek-Australian girlfriend Costeen Hatzi

Nick Kyrgios

Nick Kyrgios may be enjoying himself winning on the doubles court, but he is having just as much fun off it by splashing the cash in a shopping trip with his new girlfriend Costeen Hatzi.

He took his Greek-Australian girlfriend to a Dior store in Melbourne on Wednesday in between games at the Australian Open, The Daily Mail reported.

An employee at the store shared a photo on Instagram of the happy couple with their new $5,800  Dior Saddle Bag purchase as they posed next to a shop attendant.

Hey, big spender! Former World No. 13 Nick Kyrgios took his new squeeze Costeen Hatzi to a Dior store in Melbourne on Wednesday in between games at the Australian Open

It’s not the first time the 26-year-old has splashed out on his 21-year-old girlfriend.

He bought her a $3,450 Louis Vuitton handbag earlier this month, and Costeen later described herself as “one lucky girl” on Instagram.

'One lucky girl': Nick bought Costeen a $3,450 Louis Vuitton handbag earlier this month, and she later described herself as 'one lucky girl' on Instagram

The pair are so smitten with each other, they’ve even started wearing matching outfits.

Twinning: The pair are so smitten, they've even started wearing matching outfits

Costeen has been watching all of Nick’s games at Melbourne Park and has been described as a key member of his team.

She showed her support in the crowd on Sunday for Nick and Thanasi Kokkinakis’ third round doubles match against Ariel Behar and Gonzalo Escobar.

By his side: Costeen has been watching all of Nick's games at Melbourne Park and has been described as a key member of his 'team'

It comes after Russian tennis star Daniil Medvedev beat Nick in a four-set win at the Australian Open last Thursday.

Following his second-round loss, Costeen shared a tribute to her beau on Instagram, saying he put on a winning performance despite losing to the world No. 2.

“So proud of you. Played an amazing match… Still a winner in my eyes,” she wrote.

Nick, who went Instagram official with Costeen last month, is still in the Australian Open playing in doubles alongside Kokkinakis, where the pair are ripping it up.

The Greek-Australian duo are looking for their first doubles Grand Slam of their career on home soil.

Nick Kyrgios and Thanasi Kokkinakis won their doubles semi-final, ensuring a historic All-Aussie final at the Australian Open.

The pair beat Spanish-Argentinean duo Horacio Zeballos and Marcel Granollers 7-6, 6-4 in front of a packed crowd at Rod Laver Arena.

Kyrgios and doubles partner Thanasi Kokkinakis has become the talk of the Australian Open during their surge to the Grand-Final.

“I’ve played a lot of singles matches around the globe, but this week with Thanasi in front of these crowds, nothing beats this.”

Nick said: “My goals is only to bring new fans… that’s what I’m about. That’s what I want to bring.”

Kokkinakis said: “It’s about the crowd, not about disrespecting our opponents”

READ MORE: Liv Hovde wins in straight sets over Greece’s Michaela Laki 6-4 6-0 Australian Open Juniors.