Leinster had been dominant against the Premiership leaders in the first half, with Cullen adding that credit must go to Northampton for coming into the game after the turn.

"You can try and sit and protect what you have, that can be the real challenge," he added.

"Can you try and push on at that stage? We maybe struggled with that a little bit, but credit to Northampton as well. They dug in well defensively and made life tough for us.

"You're playing knock-out games, so the team that's behind is going to be doing everything in their power to come back into the game and make it as tight as possible.

"It's not like anyone thinks we're going to roll these guys over. Nobody is thinking that at any point. At 20-3, we're not thinking it.

"The most important thing is that you get over the line, and we managed to get over the line thankfully."