New Zealand will face the best the British and Irish game has to offer over the next three weekends and Umaga concedes how well both sides bond and handle the pressure could prove to be the key.
He said: "Bringing them [the Lions players from four unions] together and how they gel will be very important for them. To get that understanding that's developed in say your club side or Super 12 side where you are together for five or six months, is crucial.
"It's the same for the All Blacks we have to get it together in two weeks. You're trying to condense what the Super 12 sides do in six months into two weeks and develop that bond, that intuitive knowledge of each other, the little things like that you don't really think about."
Graham Henry, who coached the 2001 Lions on their tour of Australia, could end up being New Zealand's secret weapon, although Umaga is playing down that idea.
"He might have a personal touch with some of the players but with video these days everyone knows how everyone's playing," added the 32-year-old.
"They have been out of the game up there for a while so they might not know the new guys coming in. But if you've seen them on TV then there's obviously going to be videotape footage of them.
"We get the Celtic League and the European Cup so everyone knows what everyone's doing."