It's a meeting of old and new on Tommy Tiernan's new lunchtime show on RTÉ 2fm as fellow comic Al Porter arrives as his first mystery guest.

Listen to Al and Tommy sail close to the wind live here right now

Tiernan's new four-part Saturday chat show comes with a twist - the comedian won't know the identity of his guests until they walk on stage.

Speaking about the new Tommy Tiernan Show, which comes live from Dublin's Sugar Club, Tiernan said: "One of the great things about the old Late Late Show was not knowing who the guests were until they appeared on screen . . . so I just thought well, how would it be if the host didn’t know who they were until they walked out either".

The improvised lunchtime show finishes its four-week run on Saturday, July 25 in Dublin’s Iveagh Gardens as part of the Vodafone Comedy Festival. 

Tiernan is no stranger to RTÉ 2fm and previously presented a weekend show with his friend Hector Ó hEochagáin.