Ajla Tomljanović is set to reunite with her ex-boyfriend Nick Kyrgios as they team up for the inaugural United Cup in Sydney.

Tomljanović, 29, who is now Australia’s top female player following Ash Barty's retirement, will be headlining the Aussie team alongside ex Kyrgios and Alex de Minaur at the tournament from December 29 to January 8.

She and de Minaur are pairing up in the Mixed Doubles while Kyrgios, 27, is to play alongside Zoe Hives.

Speaking of her former relationship with Kyrgios, Tomljanović, 29, admitted she hasn't had much time to hang out with her former partner but is excited to join forces with the tennis champion.

'It has been like a billion years ago, I only remember it because you guys bring it up really,' she told the Daily Telegraph.

'We haven’t really had the chance to hang out but this team is just so good at having good banter and camaraderie and however it goes is going to be a super fun week for all of us.'

Kyrgios dated the Croatian-Australian tennis ace for about two years until 2017.

They reportedly went their separate ways after Kyrgios was seen leaving a London nightclub with two women in 2017, after which she scrubbed him out of her Instagram page. 

The 2022 Wimbledon men's singles finalist now dates Sydney-based influencer Costeen Hatzi, and the loved up pair are tipped to get married and start a family as early as next year. 

Meanwhile, Tomljanović dated Italian tennis player Matteo Berrettini and publicly confirmed their relationship in October 2019. They announced their split earlier this year.

Kyrgios is also facing allegations he assaulted another ex-girlfriend, Chiara Passari, in Canberra last December.

He is attempting to have the common assault charge dismissed on mental health grounds.

Kyrgios will next appear in the ACT Magistrates Court in February.

Tomljanović was disappointed when asked if she was an alleged domestic violence victim at the hands of Kyrgios after losing to Kazakhstan's Elena Rybakina at Wimbledon in July.

'I'm not really aware of exactly what's being said about his past relationship and the allegations,' she said at the time.

'It's been a while since our relationship ended. I've always kept my relationships very private. I would like to keep it like that.

'I'm definitely against domestic violence. I hope it gets resolved. 'But, yeah, I mean, I haven't had that experience with him.'

Kyrgios recently revealed he was looking forward to some more time off in the lead up to the festive season.

'I’m not going to play any more [before Christmas],' he told the Sydney Morning Herald.

'I don't want to sacrifice time at home. If I play more I don’t have that time at home, especially with the way my mum is progressing, being here with my girlfriend at home in Sydney.

'I don’t want to give up too much time on the road. Five or six months on the road is more than enough for me.'