Singer Donny Osmond broke down in tears during a TV interview when his eldest son told him he's set to be a grandfather for a fifth time.

The Puppy Love hitmaker was filming a segment on The Talk with son Donny Osmond, Jr. on Thursday when he was surprised by an early gift ahead of Father's Day on Sunday.

The eldest of the pop star's five sons told Osmond that he was expecting a child with his wife Jessica Nelson, who he married in 2010.

Upon hearing the news, the stunned crooner welled up, before jumping to his feet in celebration.

Giving his son a hug, he said: "Now I feel really old!"

Osmond already has four grandkids. The episode will air on Friday. (MJ/US/PAW)