Marc Thompson said the "hardest thing is not knowing" where his twin brother Ben is.
The 34-year-old from Haverfordwest has been missing since Saturday, after he watched Wales' Six Nations game at the Millennium Stadium.
He told our Correspondent Carole Green that this would be "very out of character" for him not to contact his family.
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In this today's Newsweek Wales, Carl talks about cancer survival rates in Wales and the search for volunteers to train guide dog puppies.
It'll be brighter today with some lingering blustery showers. This evening it'll be colder under clear skies, with isolated showers.
Gareth Bale put any domestic troubles behind him as he starred in Wales' emphatic 3-0 win over Israel in Haifa.