The All Blacks are fine tuning their preparations as they prepare to take on Australia in the first match of the tournament this weekend.
Australia have reportedly been studying the Lions' defensive work, with a rush defense working well in the drawn series earlier this summer.
Barrett insists his team have been working on countering that tactic and they are confident of defending their title in 2017.
Speaking ahead of the game, he told reporters: "Some teams in Super Rugby adopted that style of defense too, and we do understand it puts the person with the ball under a bit more pressure. But ... there are opportunities elsewhere.
"We were perhaps tested in areas where we haven't been before, so that's exactly what we wanted.
"We ask those hard questions of ourselves and of our team mates and it gets the best out of the team. It is just what we needed."