Stamkos was the first pick in this year's NHL draft. He earned his first point with an assist Tuesday in a victory over Toronto and picked up another assist Thursday when he posted a three-point night.
Jussi Jokinen scored for the second straight game and Vincent Lecavalier added two assists, boosting the Lightning to their third win in four games. That streak follows a season-opening, five-game losing skid.
Olaf Kolzig got the win, saving 29 of 31 shots.
After going through the first seven games of the season without a loss in regulation, the Sabres have dropped three in a row. Ryan Miller allowed all five goals on 40 shots.
Buffalo had won the previous five meetings with Tampa Bay.