Tonga have never beaten the hosts in eight tests and will face a Wales team ranked third in the world and on a seven-match winning streak, including victories against France, South Africa, Argentina and Australia.
Wales have made 14 changes from the team that edged the Wallabies 9-6 last weekend and Tonga head coach Toutai Kefu said that could work in their favour.
"It's not their strongest team and there's a few debutants in there, there's a few players coming back from injury, there's a few players who haven't played for a while in the red jersey for them," said Kefu.
"We're going to try and take advantage of that as much as possible but we're going to just concentrate on what we can do and what we can control. We've got a simple game-plan but we're more worried about what we're going to do than what they're going to do."
Tonga opened their Northern Tour with a 49-38 victory against a French Barbarians team in Bordeaux last weekend.
Kefu said they will stick to their guns and take a direct approach against the Welsh at the Millenium Stadium.
"They don't give you much and they defend very well so we're going to try, we've got a few little strategies to try and keep us in the game, and hopefully when some opportunity present itself we will be able to take advantage of them," he said.