Defence coach Shaun Edwards admits the World Cup schedule may favour Wales slightly against Samoa but says they need their extra recovery time.
Wales began their campaign on Sunday with a 17-16 loss to South Africa while Samoa did not start until Wednesday.
Samoa romped to a 49-12 win over Pool D minnows Namibia to set them up for Sunday's clash with Wales in Hamilton.
"I supose that gives us a slight advantage, but some of our guys are still pretty sore," Edwards said.
"The game against South Africa really was a tough game but... the best way to prepare for a tough game is to have a tough game.
"We certainly had that last Sunday and we're expecting the same this Sunday."
Wales escaped further injuries against the Springboks and have British and Irish Lions pair, fly-half Stephen Jones and prop Gethin Jenkins, in contention for selection after recovering from the injuries that kept them out of warm-up games.
Despite scoring six tries against Namibia, including a hat-trick for Leicester wing Alesana Tuilagi, Samoa did not have it all their own way and have injury concerns over fly-half Tusi Pisi and flanker Taiasina Tuifua.
Goal-kicker Pisi suffered a hamstring problem, while Tuifua was left with rib trouble that saw both players exit the game in the first half at Rotorua's International Stadium.
Samoa coach Titimaea Tafua said: "That's a worry for us. The medical people are still working on it, we'll know more tonight.
"I haven't had time to talk to the medical staff yet, but I do hope it's not serious."
Samoa captain Mahonri Schwalger was happy with his team's performance but said that thoughts would now turn to the clash with Wales.
"I'm pretty happy with the way the boys played in their first game, we will enjoy this win and then think about Wales tomorrow," he said.
"I think Wales put on a good fight against the South Africans. This week is going to be different, the team that wants it more will come out on top."