Lightning head medical trainer Tommy Mulligan said star center Steven Stamkos is complaining more about a sore jaw than concussion symptoms.
That is a big reason Mulligan on Thursday called the concussion Stamkos sustained at the world championship in Germany mild.
"Maybe (he has) a little headache, but nothing that would send out any red flags as far as memory issues or disorientation," Mulligan said.
"We have no reason to believe it's a serious issue."
Even so, assistant general manager Tom Kurvers said, "There's plenty of concern. I don't want to downplay that. We're watching and listening and gathering information as best we can."
Stamkos, playing for Canada, was hurt during Wednesday's 4-1 loss to Switzerland when he checked Timo Helbling and took on the jaw what Canada coach Craig MacTavish said was "a pretty good elbow" from the Swiss defenseman.
Stamkos, who was wearing a mouth guard that Mulligan said "absolutely" mitigated the effects of the blow, missed about 10 minutes of the first period, played the second and missed the third. He also missed Friday's game against Norway.
Kurvers said there are no immediate plans to bring Stamkos home, though if his symptoms persist, it is an option.
Tampa Bay certainly is not going to take chances with the second-year center, who at 20 is one of the league's most explosive and dynamic players, and tied Pittsburgh's Sidney Crosby with a league-best 51 goals.
"We'll make decisions as we gather more information," Kurvers said. "If we think there's an issue, I'm sure that Hockey Canada's doctors will inform us that it's more serious than we originally thought, but we don't have that kind of information right now."
The Lightning are confident it is getting the information necessary. Mulligan said he spoke to Stamkos and "from the time of the injury" has been in contact with Canada's medical staff.
"They're doing a great job," Mulligan said. "They're being extremely conservative with him, which is what we would do. They're following the identical protocol and treatment we would. We're completely comfortable with what's going on there. (Stamkos) already has made significant improvement."
The next step is getting Stamkos on a stationary bike to see if he can exercise strenuously without symptoms. Stamkos also will have to practice symptom-free before being cleared to play.
"We're proceeding with caution," Kurvers said.