Pittsburgh made a push in the third period starting with Phil Kessel's eighth goal, a wrist shot that beat Vasilevskiy on the stick side that made it 4-1 at 1:18. Nick Bonino was able to control a loose puck off a bounce and sent a pass to Kessel in stride with a clear path to the net.
"There's no comfortable lead in this league," Letang said. "Sometimes things aren't going to go your way and you have to refocus. We're capable of doing a lot of things out there, but you have to have the right mindset. You saw that in the third period."
Evgeni Malkin scored his first goal since April 28 to make it 4-2 at 11:13. Chris Kunitz scored a power-play goal off a rebound with 6:52 left to make it 4-3.
"If you look at the series, whoever is going to win the 50-50 battles and put pucks in deep [will win]," Kunitz said. "If you start turning pucks over, [Tampa Bay] is potent on the rush. They score goals, they like to spread the zone and hit guys late [with passes]. We have to do a better job to make sure we have the details down and putting pucks in deep and play more in their end."
Penguins defenseman Trevor Daley left the game with 9:07 left in the second period after taking a hit from Callahan on the boards. Daley was unable to put any weight on his left leg as he was helped off the ice. Sullivan did not provide an update afterward, but Daley left the arena on crutches.