Ireland had been in control in Paris thanks to four Sexton penalties until Teddy Thomas found a rare gap in the green defensive wall, jinking past Conor Murray before streaking away to score from 60 metres out.
The conversion took France into a 13-12 lead and as Ireland plugged away 40 metres out from, it looked as though Joe Schmidt’s side would come away from Paris with nothing more than a losing bonus point and a few cuts and bruises.
However, Sexton knew he had the distance and kicked a dramatic drop-goal from just inside the French half to grab an invaluable away win, just as he had for Schmidt’s Leinster at Treviso in September 2012.
“I went back to many years ago when we played Treviso away and I was in that exact same position, almost identical situation, and I just flashed back to that. I had a pop,” Sexton said.
“The lads’ legs were out and I don’t think we could have gone another couple of phases so just got there in the end.
“The management drill us every day that it’s never over and we’ve got some good characters in the team and we just wanted to get off to a good start.
“It looked like it was going to be deja vu when it was 9-3 at half-time, same as two years ago, then they get a try out of nothing.
“This year, we got a chance and we took it.”
Sexton also admitted he was disappointed not to have extended Ireland’s lead beyond the reach of Thomas’ try.
“It was one of those moments. I was just happy I got another chance,” Sexton added, having missed his first Six Nations place kick for two years earlier in the game.
“I had a kick to go two scores clear and I just snatched at it. At the last moment something caught my eye.
“I was just happy to get another chance to get the victory for the boys. We’ve worked so hard for the last two weeks.
“All that would have crumbled today if we had lost. It’s great to be in the position that we are now after getting an away win.”