Is Joe Biden the source of the proverbial 'luck of the Irish'?

It's a question both Irish and New Zealand rugby fans will be asking after the United States President played a hand - for the second time - in an Ireland team's defeat of the All Blacks.

Ireland dominated the visiting New Zealanders on Sunday morning in recording a 29-20 victory in Dublin, the side's third win in the match-up since 2016.

On that occasion in Chicago, then-Vice President Biden attended the match to support his cousin, Rob Kearney, and witnessed the country's maiden victory over the All Blacks.

Now it has emerged that Biden has seemingly inspired the Ireland side once again after a letter he sent to the team on the eve of the test was released to the public.

He said: "I wanted to send you my best wishes as you face the New Zealand All Blacks tomorrow.

"I was thrilled to congratulate the entire team, especially my cousin Rob Kearney, back in 2016 when you first beat the All Blacks in Chicago - a historic moment in Irish rugby.

"Since then, you've beaten the All Blacks in 2018, and I know that you can do it again this year.

"Your fans in Aviva Stadium, throughout Ireland, and around the world will be rooting you on to another victory.

"As the Irish blessing says, 'Wherever you go and whatever you do, may the luck of the Irish be there with you'."

Biden, who claims to have played rugby for a year in the mid-70s and remembered watching the All Blacks "wreak havoc" against Ireland at the time, also had a video call with the team after the match as they celebrated the win in their hotel.

"We're really proud of you guys," Biden can be heard saying on the call.

"By the way, when I was down in New Zealand not long ago, I was bragging about you guys and they almost didn't let me off the island. Congratulations fellas! We are gigantic fans."