Steven Tyler cried "like a baby" when he found out his daughter was going into labour.
Liv Tyler welcomed her second child into the world on Wednesday (11.02.15) and whilst she was in labour, the Aerosmith frontman was being given updates "minute by minute" by his daughter, Mia.
Writing on his Facebook page, Steven said: "When I got the call that Liv Tyler was going into labor, after crying like a baby myself, I immediately dropped everything and went to to the airport to get on the next available flight...
"When I landed I kept calling my daughter Mia Tyler who was already helping Liv and she kept giving me minute by minute updates,"HURRY THE BABY IS COMING!"
"I made it RIGHT in time before my second grandson entered this world. It was another (God wink) moment of a lifetime for me (sic)"
Meanwhile, Liv - who already has son Milo, 10, with her ex-husband Royston Langdon - confirmed their happy news via a spokesperson earlier this week.
A representative for Liv and her partner David Gardner said at the time: "He's healthy and everyone is very happy."
The 37-year-old actress has previously admitted she was "longing" for another child.
She said: "For seven years, I'd been saying I wanted to do an HBO show with an ensemble cast. And I wanted the house in the country. And getting to have another child? If you knew me well, they were the things my heart longed for. And they all came together, like a speeding freight train, in one year."