Tampa, Fla. ? Looking nothing like the goalie who dominated the first three rounds of the playoffs, Tampa Bay’s Nikolai Khabibulin — like the rest of the Lightning — had a shaky debut in the NHL’s championship round Tuesday night.

Khabibulin allowed three goals in the first two periods, and the league’s highest-scoring team in the postseason failed to take advantage of numerous opportunities to turn a disappointing night around in a 4-1 loss to the Calgary Flames.

“I thought a few guys were jittery … but I thought as the game wore on they wound up finding themselves,” said Lightning coach John Tortorella, whose team finds itself trailing in a series for the first time in these playoffs.

Game 2 is Thursday night.

“It’s going to be a long series,” Tampa Bay forward Fredrik Modin said. “They got the first one. We have to make sure we’re ready for the next one.”

After taking a 1-0 lead on a flukey goal three minutes into the game, the Flames broke it open with two unassisted goals in a 2:47 span of the second period — one of them a short-handed score that Calgary star Jarome Iginla slammed in after Khabibulin stopped him on a breakaway.

The goal made it 2-0 when it looked like Tampa Bay might be on the verge on tying the score, was set up when Dave Andreychuk’s pass skipped over Modin’s stick into the neutral zone. The speedy Iginla chased the puck down, batted it ahead before catching up again and firing at Khabibulin, who finished with 15 saves.

The Tampa Bay goalie got his glove up to make the stop, but an alert Iginla stopped on a dime when he saw the puck skip to Khabibulin’s right.

Modin, thinking the puck went over the net circled to the left, leaving Iginla wide-open.

“I saw him make the save … and then (the puck) disappeared,” Modin said.

Offensively, the Lightning waited for a spark that never came.

Martin St. Louis broke through on the power play early in the third period, but that was all the damage the Lightning could do against Calgary goalie Miikka Kiprusoff, who stopped 23 shots.