Headline acts at the show include Craig David, Ne-Yo, Kelly Rowland, Sean Paul and Kelis, Concertgoers took to social media swiftly after Delta's surprise appearance, with one person writing on Twitter: 'Excuse me is this magic mike rn?
''Just saw @Delta Goodrem on stage at #rnbfridayslive in Sydney!!!!! Delta showed off her own Rnb dance moves last month, taking to the stage for The NRL Footy Show finale.
Seal, 55, who split from wife Heidi Klum in 2012, told Australia's New Idea magazine that he has a lot of respect for his co-star, 32, branding her a "national treasure".
Their fellow Voice judge Boy George recently opened up about the pair's rumoured relationship, explaining that he is convinced Seal is attracted to the glamorous singer.
During an appearance on Australian radio's The Kyle And Jackie O Show, he said: "I might be being controversial but I think Seal fancies the pants off Delta...
Host Larry cheekily prodded the Packed To The Rafters star, saying: 'We see photos...
and we go "okay, put a ring on it, have kids, let's get this next chapter going."Hugh then responded: 'We talked about it I just don't think so.
The denial comes after Woman's Day reported that the pair were exploring baby options, with the Voice coach's mum Lea completely on board.'She's been exploring all her baby options and she really thinks Hugh would make a great dad - even if it were an unconventional scenario,' the source told the publication.'Lea loves Hugh and thinks he is just the best.