Nick Kyrgios has surprised his fans by announcing he'd like to have four children in a social media post he quickly took down on Sunday.

The Aussie tennis star often takes questions from his millions of follwers on Instagram and when one asked him, 'How many kids you want?' he replied with a simple '4' - only for his answer to disappear soon after.

It's not the first time the 27-year-old has spoken out about his desire to have children with girlfriend Costeen Hatzi.

During another Instagram Q&A session in July last year he answered 'very soon' when a fan asked 'when are we having babies' - then followed that up by telling another supporter that he wanted to marry Hatzi 'very soon'.

He had previously hinted at a wedding and some little Kyrgios kids in a playful interview with Today's Karl Stefanovic last March, and doubled down on his plans to wed Hatzi earlier this month when he posted 'our wedding soon' after seeing photos of his partner posing with a baby online.

Kyrgios has happily credited Hatzi's positive influence with helping him produce the best year of his tennis career in 2022.

He called her the 'best girlfriend in the world' as he applauded his support crew in July last year as he closed in on his appearance in the Wimbledon men's singles final against Novak Djokovic.

'In the past when I've got this far in a grand slam or I've played big matches, I haven't been able to separate ... I used to be on my phone a lot after matches like this,' he said.

'But I feel like I’m really able to switch off from that. And that’s a big part of my growth. Obviously being obsessed with my girlfriend helps.'

The world No.21 is currently recovering from surgery on the knee injury that ruined his Australian Open campaign and opened himself up to questions from his 3.3million followers this weekend with the words 'Alright let's do some fun ones today'.

When a fan asked 'If you could only save one person, Thannis [his best friend Thanasi Kokkinakis] or Cos, who would you choose?' he replied, 'I think I would have a kid and call him thanasi, would have to save my girl.'

He picked Jayson Tatum of his beloved Boston Celtics to be named the NBA's most valuable player when prompted by another follower, and wrote 'Appreciate you!' when another supporter said, 'I love your rebellious energy. Keep doing things your way.'

Kyrgios is aiming to make his comeback from the knee injury at the Indian Wells Masters in early March and is already back in the gym.