But the star forward, who has been out of action since early April after undergoing surgery to remove a blood clot in his right collarbone area, remains hopeful of playing in this series against the Pittsburgh Penguins.
"I'm hoping there is a chance for [Game 3] or the game after that," Stamkos told reporters Monday morning after taking part in an optional workout.
That said, Stamkos also warned that doctors may not ever feel it's safe for him to play this season given that he is taking blood thinners as part of his recovery protocol.
"We could come to the conclusion after all of our research that it's just not safe to play at all in these playoffs," Stamkos said. "That's the reality I'm living with. That's the tough part right now. I'm just trying to give myself a chance so if that day comes where we speak with the docs and we feel as a group -- me, my family -- that it's safe to get back on the ice, I'll [be ready]."
Stamkos has been skating with his teammates for several days after not traveling with the team at the start of the playoffs. He did drills involving some contact Sunday but said that Monday he will need to do more of that before he can contemplate game action.
He must also face the overarching issue of how to balance the use of blood thinners with playing, as any kind of cut could have dangerous repercussions for someone on blood thinners, making it unsafe to play while the medication remains in the body.
"There are certainly guys who have played in the NHL with the same medication I have been on, altering the routine," Stamkos said. "That's something we are experimenting with. It's just a matter of how long you have to be on the twice-a-day injections versus if you played, you would have to skip an injection.
"I'm in a holding pattern. There's still a chance I can play in this series, there's still a chance I might not play the rest of the playoffs. That's honestly the truth."
The Lightning lead the Eastern Conference Finals 1-0 with Game 2 set for Monday night and Games 3 and 4 in Tampa on Wednesday and Friday.