They may be locked in a ratings war.

But KIIS FM’s Kyle Sandilands has sided with his radio rival, Nova FM star Tim Blackwell, amid the backlash surrounding his much younger girlfriend, Lizzie Baxter’s, Father’s Day post.

Fans were left stunned when Lizzie, 28, uploaded a photo of Tim, 42, and his three young children alongside the caption: ‘Happy Father’s Day to our Daddy because I’m young enough to be your daughter too.’

While the joke largely fell flat online, Sandilands, 54, has rushed to support the couple, arguing that Lizzie’s quip was ‘kind of hot’.

‘Funny. Nothing wrong with that. Let me tell you, no fan gives a s**t about Tim Blackwell if his missus is calling him daddy. To me, that’s kind of hot,’ he added.

Sandilands, who is 15 years older than wife Tegan Kynaston, also hit back at ‘revolting’ criticism of the age-gap couple, calling the backlash ‘nasty’ and ‘unnecessary’.

KIIS FM’s Kyle Sandilands, 54, has defended his radio rival, Nova FM star Tim Blackwell, 42, amid the backlash surrounding his much-younger girlfriend Lizzie’s Father’s Day post. (Left is Kyle Sandilands, right is Tim Blackwell and Lizzie Baxter)

Sandilands, who is 15 years older than wife Tegan Kynaston (left), hit back at ‘revolting’ criticism of the age-gap couple, calling the backlash ‘nasty’ and ‘unnecessary’

It comes days after Nova listeners expressed disgust over Lizzie’s questionable Father’s Day tribute.

‘Yuck and vomit,’ wrote one follower.

‘Sorry, there is a better way to recognise your partner on Father’s Day,’ commented another.

‘Calling him Daddy. Yuck,’ wrote one more, before a fourth labelled the questionable post, ‘Vomit stuff.’

Tim shares children, Bo, 12, Alfie, nine, and Artie, six, with his former wife Monique.

Tim and Lizzie made their red carpet debut at the ARIA Awards in November last year.

Tim, who was hosting the annual music awards ceremony, officially confirmed their relationship to Daily Mail and said Lizzie, a producer on Nova’s Fitzy & Wippa, was his ‘date’.

The pair looked smitten as they embraced and posed for photos at the media wall.

Posting a photo of herself posing alongside her sweetheart and his three young children, Lizzie captioned the snap, ‘Happy Father’s Day to our Daddy because I’m young enough to be your daughter too.’ Nova listeners were not impressed (Pictured)

‘Funny. Nothing wrong with that. Let me tell you, no fan gives a s**t about Tim Blackwell if his missus is calling him daddy. To me, that’s kind of hot,’ he said. (Pictured are Lizzie and Tim Blackwell)

Lizzie put on a leggy display in a tartan off-the-shoulder mini dress, which she paired with racy thigh-high stockings.

The appearance came just one day after Daily Mail revealed their romance following a date in Coogee.

Joined by their Nova colleagues, the couple stayed close as they attended an intimate ‘Red Room’ gig at the Coogee Bay Hotel, hosted by rapper The Kid Laroi.

The lovebirds are believed to have started dating after Tim’s marriage broke down.

In a flirty exchange on social media, Tim announced he was hosting the awards show and Lizzie asked in the comments if she could be his date for the evening.

‘Do you need a date by any chance? You’re hot,’ she wrote.

‘I’ll be working. Wouldn’t that be unprofessional?’ Blackwell responded, before quickly adding, ‘I’ll think about it…’

She teased in reply: ‘Hasn’t stopped you in the past.’

Tim and Lizzie’s romance came almost one year after his estranged wife Monique confirmed they had split.

Monique, an entrepreneur and yoga instructor, broke the news via Instagram on December 10.

‘Not all good things end, but this has,’ she captioned a gallery of photos of herself with Tim in happier times.