The worst start of their best-of-7 series led to the Bruins’ 4-1 loss to the Lighting on Wednesday night. The B’s will try to even the series on Friday night at TD Garden.

Mike Loftus The Patriot Ledger

BOSTON -- For a couple of games, it didn’t amount to much more than a nibble.

On Wednesday night, it really bit the Bruins.

Their start to Game 1 of the best-of-seven playoff series against the Lightning wasn’t great, but the B’s at least defended well enough to stay even, took a 1-0 lead late in the first period, and went on to win 6-2. The start to Game 2 was a little worse, but the Bruins were still tied, 1-1, entering the second period of a road game they’d ultimately lose, 4-2.

The Bruins were essentially non-starters in Game 3 on Wednesday night, and they’re behind in the series as a result. The worst period of the playoffs -- 19 shots and three goals against -- doomed them to a 4-1 loss, and a day or so of soul-searching before Game 4 on Friday night at TD Garden, where they’ll try to square the series at 2-2.

“It was a bad start. There’s no question about it,” said center Patrice Bergeron, the Bruins’ only scorer. “They obviously jumped on us, and scored some big goals, and we couldn’t get back in the game.”

The Bruins were actually close to getting back into it, but a period-long failure to play sufficient defense killed them.

The Lightning goal that answered Bergeron’s power-play strike typified all that was wrong with the B’s: They did a poor job of breaking the puck out of their zone, a poor job of retrieving it when the Lightning dumped it back into their zone, and no job at all once Anthony Cirelli took a pass from Yanni Gourde in the right circle: Cirelli was basically untouched as he fanned on his first shot attempt, was denied by Tuukka Rask (33 saves) on the second, and finally scored on the third.

“We didn’t defend well enough in the first period. That was our major issue,” said Bruins coach Bruce Cassidy, who chalked that up in part to a deficiency in intensity and urgency that he began to speak about after Game 2, and addressed before Game 3 by pulling fourth-line winger Tim Schaller -- who had played all 82 regular-season games and the first nine this postseason -- from the lineup in favor of Tommy Wingels.

“We need to defend better. Part of that is intensity, in my estimation -- urgency, pick your word. We didn’t have it.”

Down 1-0 after a one-of-those-things goals -- rookie defenseman Matt Grzelcyk misplayed a dumped-in puck, and Tyler Johnson fed Ondrej Palat for a quick 2-on-1 marker after just 1:47 -- the Bruins made things worse by allowing the Lightning to sustain pressure two shifts later. That turned into a net-front deflection credited to Palat at 3:19.

“We turned away, or didn’t tie up” in front of Rask, Cassidy said.

“Of course, you’ve got to score at some point, but if we take care of our business there, it’s a 1-1 game, because we got one back. We’d be fine, and then we’d just play.”

Things weren’t fine for long after Bergeron’s power-play goal at 14:12, though. A sloppy exit from the defensive zone, followed by even sloppier coverage, let Cirelli make it 3-1 just 2:31 after Bergeron scored, and only 3:17 before the first period ended.

The Bruins couldn’t solve another recurring them -- puck possession, or the lack of it -- after that. While they did land a series-high 29 shots on Andrei Vasilevskiy, only 15 came over the first two periods. The Bruins never got a power play after Bergeron’s goal -- the second time in the series they’ve only been awarded one manpower advantage.

Cassidy tried to address the absence of offensive pressure in different ways, like giving the Brad Marchand-Bergeron-David Pastrnak and Jake DeBrusk-David Krejci-Rick Nash lines extra shifts and pairing offensive defensemen Torey Krug and Charlie McAvoy together, but without much success. The coach hadn’t decided yet what he’d try in Game 4.

“I think it’s easier to do the next morning than immediately after the game,” the coach said. “If we want to win hockey games, we’re going to have to be better on Friday. There’s no doubt.”