Six Nations: Wales hang on for vital win after Ireland's Peter O'Mahony red card

Wales overcame a poor start to defeat 14-man Ireland 21-16 in their opening Six Nations clash at the Principality Stadium in Cardiff, easing the pressure on coach Wayne Pivac.

Wales played with an extra man for 66 minutes after Ireland flanker Peter O'Mahony received a deserved early red card, but trailed 13-6 at halftime as they offered little in terms of creativity and quality in the opening period.

But as Ireland tired with their numerical disadvantage, Wales found space in the visitors 22, and centre George North and wing Louis Rees-Zammit crossed for tries, to go with three penalties and a conversion from fullback Leigh Halfpenny.

Ireland will rue the early red card but were still the better side in the first half as they crossed for a solitary try through lock Tadhg Beirne, and showed plenty of heart in the second period to stay in the contest.

The visitors had one final opportunity when they kicked for the corner for an attacking lineout five metres out, but replacement flyhalf Billy Burns booted the penalty too long and referee Wayne Barnes blew the final whistle to cap a frustrating afternoon for the visitors.

There will be relief for Pivac, who won just three of his first 10 tests in charge of Wales last year, beating Italy twice and Georgia, and had promised a much-improved showing in this Six Nations.

"It was a nail biting last few minutes for us but it's nice to get over the line and start the tournament with a win," Wales captain Alun Wyn Jones told the BBC.

"We just had to win today. It's key to start with a bang and keep momentum going so we are happy.

"Sometimes it is tough to play against 14 men because they front up. We were on top until that moment (the red card) and then we seemed to ease off a bit."

O'Mahony was sent off for a dangerous entry into the ruck. He flew into a collision with a stranded Tomas Francis, providing no arms in the engagement with his shoulder leading into the side of the Welsh prop's head.

"I'm proud of the boys for the effort we put in, but ultimately it came down to a few key mistakes," Ireland captain Sexton said.

"I think a couple of decisions at the end went against us, but Wales are a very good side and we only have ourselves to blame.

"We spoke about discipline in the week but it let us down and we made some key errors."