The boy band are very excited that their former 'X Factor' mentor and his newly divorced girlfriend Lauren Silverman are expecting their first child in February and have no doubt he will be a great father.
Niall Horan, 19, told UsMagazine.com: "He's going to be sick. He's a really nice, great guy."
His band mates Harry Styles, 19, added: "He's going to be great."
Simon recently joked that he already felt like father after spending so much time with the 'Kiss You' hitmakers.
Speaking at the world premiere of the band's new 3D movie 'One Direction: This is Us' in London's Leicester Square last Tuesday night, he joked: "This is like a dream come true... I feel like a father."
He also gushed about how much he was looking forward to welcoming his first child into the world.
He said: "I'm proud to be a dad. It's something I hadn't thought of before, but now I know I feel good about it.
"Things are changing in my life right now, for the better. She [Lauren]'s a very special girl."
The New York socialite, who is approximately 12 weeks pregnant, landed in Nice Cote d'Azur airport on Wednesday to meet up with Simon for the first time since her divorce from Andrew Silverman was finalized last week.