Ireland captain Johnny Sexton defended Billy Burns after the replacement's late missed touch helped Wales hang on to clinch a 21-16 Six Nations win.

"As a 10 you have to go for it and you have to try and put it five metres out," the Ireland skipper told the BBC.

Ulster fly-half Burns had replaced Sexton late in the second half.

The 26-year-old replacement looked distraught after the final whistle and was comforted by a number of his team-mates.

"There is a big difference between going 10 metres out and going five metres because that gives you a chance to score. Sometimes you miss and sometimes you get it and you are the hero," added Sexton, who was replaced by Burns near the end after taking a heavy hit.

Ireland fought back from 6-0 down to lead 13-6 at half-time despite Peter O'Mahony's 14th-minute red card for catching Welsh front row Tomas Francis with a leading elbow when diving into a ruck.

The Ireland skipper insisted he was "proud" of how his side had regrouped from the Munster back row's early exit but admitted that "errors" had ultimately cost them victory.

"We only have ourselves to blame," added the 35-year-old.

"We spoke about discipline earlier in the week and that let us down at key times as well as some key unforced errors."

Sexton said Ireland "re-gathered well" after O'Mahony's red card for a reckless elbow to the head of prop Tomas Francis but questioned whether several Welsh challenges went unpunished by referee Wayne Barnes, citing a tackle by Johnny Williams on Garry Ringrose.

"I'm proud of the boys and I'm proud of the effort," added the Ireland captain.

"Ultimately it came down to a few mistakes at key times and the rub of the green as well. We get red carded for a high tackle and they don't get penalised for one."