And while the man charged with leading the Lions to series success in Australia insists that next month's final selection will be based on far more than just Saturday's showings, he admits that the pressure cooker atmosphere in Cardiff will tell him a lot about some of his potential stars Down Under.
"It's a situation that you want to see players in, under pressure, and it is what we are going to face in Australia," Gatland told the Daily Telegraph.
"For me, as Lions coach, it's really exciting this weekend that it has come down to a 'final'.
"It's not a 'trial' game but it is a trial game, that's how it has worked out. You are not going to select the Lions squad just on Wales versus England but, for some players in some positions, there are key match-ups that could weigh up the decision one way or another.
"So there shouldn't be any lack of motivation. I know if I was playing I would be thinking: 'I have a chance to get myself on the plane. I'm not leaving anything in the tank.'
"I couldn't have asked for anything more than that but that's not forgetting that Scotland and Ireland have big games as well. There is a lot at stake for players in those two teams to perform on the last weekend too."
Tour manager Andy Irvine told us last week that there were still plenty of places to be filled on the 125th anniversary tour and Gatland has confirmed that he has a number of tough choices to make over the coming weeks.
"I would say consistently there has been 22 or 23 that have been on that list so I would say there is still around a third of the squad up for grabs," added Gatland, who has no plans to pick a captain until he has decided on the make up of his party.
"I think there are three or four individuals that people have been consistently been talking about (for captain) and again I think this weekend may answer one or two of those questions.
"We will pick the squad first and then look at a captain.
"When you are looking at a captain and leadership, there are a number of things in terms of how the player sets an example on and off the field in terms of discipline but also how he carries himself and the respect he earns from his fellow team-mates."