Calgary, Alberta ? Good game, bad game. Good game, bad game.

For a month, the Tampa Bay Lightning have followed an unswerving course in the playoffs — play very well in one game, play poorly in the next.

Stay to form in Game 4 of the Stanley Cup final tonight, and the Lightning will even the series with Calgary. If not, they will be very close to handing the Cup to the Flames, who are threatening to become one of the most improbable champions in NHL history.

That’s why the Lightning find themselves at a crossroads in hockey-obsessed Calgary, where the high temperature Sunday was 30 degrees lower than in Tampa, but the heat definitely was on them following their 3-0 loss Saturday in Game 3. They knew it, too.

“I know, (the talk is) Tampa Bay got beat up again and they were outworked this, that and the other thing,” coach John Tortorella said Sunday. “I don’t buy that. I thought the game was closer than 3-0, but they simply got it done. The key to winning a seven-game series is how long you can keep it (momentum) on your side, and we’ll be there (Monday) night.”

If they start matching the Flames’ intensity, commitment to defense and willingness to pay any price physically — star Jarome Iginla is doing as much fighting as goal scoring — the Lightning could quickly reverse the series.

But Tampa Bay’s superior offense needs to get better, and quickly; the Lightning have been outscored 8-5, with all but one of their goals coming in a 4-1 victory in Game 2.

The Lightning have another worry as they await the most important game in the franchise’s 12-year history. They’ve let the Flames, who have shown an ability to ratchet up their performance level whenever necessary, get tantalizingly close to a Cup that would be wildly celebrated not only in Calgary but throughout Canada.