Louis Rees-Zammit scored a try on his Guinness Six Nations debut as Wales held off 14-man Ireland to win 21-16 at the Principality Stadium.
The 20-year-old Gloucester wing pounced midway through the second half, destroying Irish hopes of a famous triumph over adversity after flanker Peter O’Mahony’s 14th-minute red card.
Munster forward O’Mahony was sent off following a reckless shoulder-led hit to Wales prop Tomas Francis’ head, but Ireland still led until Rees-Zammit struck.
Ireland also lost lock James Ryan to a failed head injury assessment, and skipper Johnny Sexton’s afternoon ended 11 minutes from time when Wales flanker Justin Tipuric’s knee accidentally caught him in the head.
But Sexton’s eight points and a try by lock Tadhg Beirne gave Ireland scent of a first Six Nations victory in Cardiff since 2013, and they mounted relentless late pressure before replacement Billy Burns missed touch with a penalty in the final seconds that would have given his team an attacking line-out.
George North’s 42nd touchdown for his country, three Leigh Halfpenny penalties and a conversion ultimately broke Ireland, despite a late Burns penalty.