Tkachuk, who missed the final 25 games of the regular season with a lower-body injury sustained at the 4-Nations Face Off, scored two power-play goals for the Panthers to cap off a three-goal second period.

Nate Schmidt scored twice, and Sam Reinhart and Sam Bennett each had a goal and an assist for the Panthers, who are the No. 3 seed in the Atlantic Division. Sergei Bobrovsky made 20 saves.

Jake Guentzel and Brayden Point scored for the Lightning, who are the No. 2 seed in the Atlantic Division. Andrei Vasilevskiy made 10 saves.

Game 2 of the best-of-7 series will be here on Thursday (6:30 p.m. ET; TBS, TRU, MAX, FDSNSUN, SCRIPPS).

Bennett gave Florida a 1-0 lead at 3:44 of the first period when he deflected a pass from Mackie Samoskevich out of the air.

Guentzel tied it at 1-1 with a power-play goal at 12:21, tucking in a loose puck off a shot from Nikita Kucherov.

Reinhart put the Panthers ahead 2-1 at 19:15 when he redirected the puck past Vasilevskiy’s glove after a point shot from Dmitry Kulikov.

Schmidt extended the lead to 3-1 at 4:41 of the second period, cleaning up a loose puck in front of the net after Vasilevskiy failed to control a save on a shot from Brad Marchand.

Tkachuk pushed it to 4-1 with a power-play goal at 4:55 when he went to the five hole to beat Vasilevskiy from the low slot. His second power-play goal made it 5-1 at 9:44, a wrist shot from the right circle that deflected off Victor Hedman’s skate.

Point made it 5-2 at 13:04 with a one-timer from the left circle off a pass from Ryan McDonagh.

Schmidt scored the Panthers’ third power-play goal at 5:09 of the third period for the 6-2 final.