So this is how it’s going to be. The Celtics shoot the lights out with 40 points in the fourth quarter of Game 1 of the NBA Finals and win, 120-108. The same Celtics can’t find the light switch in their 14-point third quarter of Game 2 and lose, 107-88.

We should not be surprised. The Celtics have played this way throughout the postseason. Up and down. Rollercoaster. Unbeatable and beatable. Win on the road. Lose at home.

But these unpredictable Celtics also have not lost back-to-back games since March, so look for them to rebound against the Warriors in Game 3 Wednesday night at TD Garden. If they don’t, they are in trouble.

Here’s what they must do to protect their turf.

Take care of the ball and avoid costly turnovers, 19 for 33 points in Game 2. Come out strong in the third quarter, a big challenge given the Warriors have outscored the Celtics 73-38 in the third. Take charge in the fourth quarter, Jason Tatum and Jaylen Brown. Stop crying about the officials and their calls and non-calls. Ignore the Warriors trash-talking Draymond Green. Let me repeat: Ignore the Warriors trash-talking Draymond Green.

The Celtics are fortunate to be in these NBA Finals. No, forget fortunate. The Celtics are lucky to be in these NBA Finals for the first time since 2010 and the 22nd time in the 75-year history of the franchise. If the Heat’s Jimmy Butler had made that three-point shot with 16.6 seconds left in the fourth quarter of Game 7 of the Eastern Conference Finals for a 99-98 Miami lead, I seriously doubt the Celtics would have won, not the way they closed out that game in Miami.

But Butler’s shot hit the front rim, and here we are, Game 3 of the NBA Finals, the best-of-seven series tied at 1-1. Buckle up! We’re in for another wild ride.

Mike Szostak covered sports for The Providence Journal for 36 years until retiring in 2013. His career highlights included five Winter Olympics from Lake Placid to Nagano and 17 seasons covering the Boston...