TAMPA, Fla. -- The Tampa Bay Lightning lost top-line defenseman Anton Stralman to a broken leg in the first period, which meant the rest of the defense had to step up, as they will indefinitely.

They did that and then some, with three defensemen scoring in the final period as the Lightning pulled away to a 7-4 victory over the New York Islanders on Friday night at Amalie Arena.

"He's an extremely important part of our team, and has been since the day he got here," Lightning coach Jon Cooper said. "But as we said in our locker room, his season is not over. Nobody's going to replace him, but ... the way we defend as a group and the depth we have, we should be OK."

Stralman went down in front of the Lightning net and suffered a nondisplaced fracture of his left fibula. He'll miss the rest of the regular season, but the team will be motivated to extend their playoff run long enough to get him back.

"That's a big loss for us. That's tough," said Lightning defenseman Jason Garrison, who had a goal and two assists Friday. "Guys have to step up and fill his void. Guys have the ability to do that, but it's big shoes to fill."

Tampa Bay moves into first place in the Atlantic Division, with a tiebreaker edge over the Florida Panthers, who come to Tampa Saturday for a key showdown.

Tied 4-4 in the third, Tampa Bay (43-26-5) got two goals in a 23-second span, with Tyler Johnson giving them the lead on a rebound for his 13th goal of the season, then Garrison scoring the sixth goal for a two-goal cushion. Another defenseman, Victor Hedman, added an empty-net goal with 1:25 to set a season high for scoring for Tampa Bay.

"You're not going to win many games in this league giving up seven goals," Islanders center John Tavares said. "Obviously the back-to-back goals there really hurt us. ... They've proven why they're a very good team. We expect a lot of ourselves to rise to a level where we're going to have success against anyone we play against."

Tampa Bay had been 0-6-2 when Ben Bishop allows four goals or more, and the two points put them even with idle Florida for the division lead, with the tiebreaker advantage.

The Islanders (39-25-9) remain the first wild card in the Eastern Conference with nine games remaining, two points ahead of Detroit and Philadelphia -- the six goals allowed by goalie Thomas Greiss matches the team's most this season.

Tampa Bay had taken a 4-3 lead in the third on a goal by defenseman Andrej Sustr with 13:57 left in the game, but the Islanders answered just 19 seconds later to tie the game. Nikolay Kulemin fired a shot past Bishop to tie the game at 4-4 with 13:38 left. It was Kulemin's seventh goal of the season.

New York also goes back-to-back with a game Saturday at Carolina, with a feeling of missed opportunity after twice rallying to tie the game Friday.

"It's embarrassing to give up seven goals this time of year when you need the points," Islanders center Frans Nielsen said. "It's not a good feeling right now. The good thing is a new one tomorrow and we've got to be ready."

The Islanders trailed 3-1 briefly in the second period before rallying back to tie the game 3-3 entering the third. The tying goal came with 3:42 left in the period as defenseman Johnny Boychuk fired a long shot from the blue line that caromed off defenseman Andrej Sustr's skate in front of the goal. It was Boychuk's eighth goal of the season.

Tampa Bay led 3-1 after Steven Stamkos scored his team-best 35th goal off a rebound on a long shot by Garrison with 14:58 left in the second. Only 23 seconds later, the Islanders pulled back within a goal as Shane Prince scored unassisted -- his fifth on the season -- to cut the lead to 3-2.

Tampa Bay jumped ahead with two goals in a span of nine seconds in the first period. Nikita Kucherov redirected a shot from Alex Killorn to tie the game at 1-1 with his 29th goal and nine seconds later, Vladislav Namestnikov followed with his 14th goal for a 2-1 lead. New York had a bad clear from behind the goal and Namestnikov had an easy shot for the lead.

Stralman went down with an injury to his left leg when he was tangled with Islanders left winger Anders Lee in front of the Tampa goal. He tripped and his skate caught on the way down, twisting his left leg. He had to be helped off the ice by teammates.

Shortly after and just as a power play ended, the Islanders took the lead as Brock Nelson scored his 25th goal off a pass from Ryan Strome.

NOTES: Both teams continue to play without key players. The Lightning again were without RW Ryan Callahan, who was sidelined for a third game with a lower-body injury, and C Valtteri Filppula (fifth, upper body). Tampa Bay also had D Nikita Nesterov as a healthy scratch. ... The Islanders have played 10 games without D Marek Zidlicky (upper body) and five games without C Mikhail Grabovski (upper body). RW Steve Bernier and D Brian Strait were healthy scratches. ... The Islanders will host the Lightning in 10 days, and the teams could meet again in the postseason.