Billy Joel and Alexis Roderick are expecting their first child together.

The 'Piano Man' hitmaker, who already has 29-year-old daughter Alexa Ray Joel with supermodel ex-wife Christie Brinkley, is reportedly ''thrilled'' that his long-term girlfriend, 33, is pregnant.

A spokesperson for the 65-year-old star confirmed the news, and a source close to the couple told ''Billy is thrilled to become a dad again.''

The duo plan to keep further details about their unborn baby under-wraps until after the birth.

The singer started dating former banker Alexis in 2009 and rumours began swirling that they got engaged earlier this year.

A source told Star magazine in February: ''They're looking at a summer wedding. He's happier than ever.''

The musician presented Alexis with a diamond ring more than two years ago, but is said to have only asked her to marry him recently.

The insider added: ''That ring wasn't an engagement ring - more like a friendship ring. But he came to realise that he wasn't being fair to Alexis. He knew he couldn't keep stringing her along forever.''

Aside from Christie, Billy was also previously married to Elizabeth Weber from 1973 to 1982, and split from his most recent wife Katie Lee in 2010 after six years of marriage.