Andy Farrell says Ireland will be kicking themselves after throwing away their chances against Wales.
The visitors to the Principality Stadium in Cardiff played more than three quarters of the game with 14 men following Peter O'Mahony’s dismissal for dangerous play.
Despite that, Ireland led 13-6 at half-time and blew a late chance to create a winning score when, deep into overtime, replacement out-half Billy Burns overshot his touchline target.
"We certainly had an opportunity to win it," Farrell told RTÉ Sport following the Guinness 21-16 Guinness Six Nations loss.
"I suppose we'll look at a few moments within the game that we'll kick ourselves about.
"Obviously the red card and a couple of decisions that could have gone our way regarding yellow cards, etc. that will be reviewed.
"On the back of that, some errors that we invited them back into the game with.
"[Peter] is gutted as well. Guys don't do this on purpose, to get sent off and hamper the performance of the team.
"They care about the team and their team-mates deeply so obviously Pete is hurting at this moment in time.
"He's done a lot of good things for us in the past and I'm sure he'll do the same for us in the future."
Asked if he had any argument with the red card, he said: "I've seen them given before so I'll let people who get paid to assess that do that."
Ulster playmaker Burns replaced Sexton in the 69th minute and Ireland drove from deep in their own half to win a penalty inside Welsh territory.
However, the out-half misjudged his kick, sending it into touch past the try line, and referee Wayne Barnes blew for full-time.
"I haven't had a chance [to talk to him] yet, but I will do. I shook his hand and then I had come to come and talk to you boys. I will speak to him, obviously," said Farrell.
"It's not the reason we lost the game. We have all missed touch before.
"I suppose he will be gutted, obviously, because of the magnitude of the last minute and whether we've got a chance to win the game at the death there, but he'll learn from this."
Captain Sexton, who also missed touch with a kick in the second half, said of the incident: "As a 10 you have to go for it.
"I said to him, 'you've got to go for it' and he did. I went for one as well [and missed touch]. When you're chasing a game, you're eight points down or, as Billy was, five points down, you've got to put it five metres out. That's when you score tries.
"If you put it 10 metres out even a good maul rarely gets over.
"Other days you're the hero when you stick it on the five. It's the life of the number 10. It comes down to small margins. I thought he did very well in the other parts of the game.
"That's one moment but there's plenty through that second half where we could have done better but it's tough with 14 men. As a 10, you have moments when you're a hero and you have moments when you're a villain."
While Ireland, who welcome France to the Aviva next Sunday, had to play with 14 men for most of the game, it was a cause of frustration for Farrell and Sexton that Wales kept their full complement for the entire tie.
There were eyebrows raised when Johhny Williams escaped any sanction for what looked like a high challenge on Garry Ringrose, while Nick Tompkins’ late deliberate knock on went unpunished beyond a penalty.
"We get told that head-on-head is a sanction, so I don't know what the mitigating factors were or what was said on the field but there's that and a few more things we'll need to go through and assess," said Farrell.
On the late Tompkins intervention, Sexton said: "For me, it’s clear. Tompkins sticking his hand out. The hand in the ruck [for the late penalty].
"I don’t know what else to say, I’m blaming ourselves for the loss but when you show the bravery that we showed, they are tough to take, again, it’s not a surprise really."
