Fly-half Tusi Pisi and flanker Taiasina Tuifua both went off during the first-half of Wednesday's 49-12 victory over Namibia at Rotorua International Stadium.
Goalkicker Pisi suffered a hamstring problem, while Tuifua was left with rib trouble.
"The medical people are still working on it," said Samoa coach Titimaea Tafua.
"We will know more tonight. I do hope it is not serious."
Leicester wing Alesana Tuilagi scored three tries as Samoa predictably had too much pace and power for Namibia.
"I wouldn't like to be standing in front of Alesana when he's in full cry," said Samoa's backs coach Brian McLean.
"I saw someone in the paper say he's 110kg, but he's actually 121kg. He's quite a sight when he is in full flight."
Samoa now have just four days before they face Wales in a pivotal Pool D match, but skipper Mahonri Schwalger is untroubled by the relatively short turnaround.
"We will enjoy this win, and then think about Wales tomorrow," he said.
"The team that wants it more will come out on top.
"I'm pretty happy with the way the boys played in their first game."
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