The Senators, after coughing up a three-goal lead in the second period, put all those bad memories behind them. Game 4 of the series is in Boston’s TD Garden on Wednesday.It was the Senators’ turn to play fast and loose with the lead after taking the Bruins to school and leading by three goals before four minutes had elapsed in the second period.Perhaps scared stiff by the drubbing, the Bruins responded and scored three times before the end of the period to knot the score 3-3 heading into the final frame.The third period was a rollicking affair with great scoring chances at both ends, but the score remained deadlocked.Ottawa goaltender Craig Anderson made a great glove save off a tough shot by Kevan Miller. “I just tried to get it up 18 inches and I got lucky that I did.”The Senators have now taken a 2-1 lead in the best-of-seven-game Eastern Conference quarter-final. The crowd kind of willed them into it.” The event capped an exciting weekend of sports in the New England city that also included an NBA postseason game between the Boston Celtics and Chicago Bulls and a weekend home stand for the Boston Red Sox.And Monday was the Patriots’ Day holiday in Massachusetts and before the hockey game came the 121st Boston Marathon, with close to 30,000 participants pounding the pavement.But the spandex set eventually disappeared, to be replaced that night by the city’s hard-core hockey fans, who haven’t had an NHL playoff game at which to vent their excitement since 2014, the last time the Bruins played a home playoff date.The fans were already in fine form before the teams hit the ice, whooping it up when the maniacal laugh of Ozzy Osbourne erupted from the PA system, signalling the start of heavy metal anthem Crazy Train.Neither team had scored a goal in the opening period in either of the first two games, but the Senators quickly halted that anomaly.Hoffman broke in behind a sleeping Boston defence for a breakaway and scored at the seven minute 15-second mark, using his long reach on a deke to slide the puck past Rask.Less than 30 seconds after that, Derick Brassard took advantage of a sloppy Boston clearing attempt, banging home the puck while stationed on Rusk’s doorstep for a 2-0 Ottawa lead.Ottawa outshot Boston 10-3 in the period.More trouble was to follow Boston into the second period, in which Hoffman potted his second, on the power play, his shot from the blue line sailing into the upper half of the net through heavy traffic to bring the score to 3-0.Even Bobby Orr, the beloved former Bruin great who was among those in attendance, must have had trouble digesting what was unfolding at ice level.But the Bruins battled back, and quickly.First it was Noel Acciari, playing in his first playoff game for Boston, deflecting a shot past Anderson.Then, just 42 seconds later, a horrible gaffe by Ottawa’s Ryan all but gift-wrapped Boston’s second goal.Ryan lost control of the puck just inside the Ottawa blue line and then fell as David Backes quickly closed ranks.Backes scooped up the loose puck and broke in all alone on Anderson to score and cut the Ottawa lead to 3-2.And the Bruins were not done yet.While on the power play, David Pastrnak wired home a shot to the short side of the net that tied the score at 3-3. “But it’s too bad we fell short.”In the first game of the playoff last week in Ottawa, it was the Senators who could not hang on to a 1-0 lead heading into the third period, in which the Bruins scored twice to take a 2-1 win.And in Saturday’s second encounter, it was the Bruins who coughed up a two-goal lead in the third period that allowed the Senators to skate off with a 4-3 overtime win.Ryan said he has no explanation for the big game swings providing the dominant story of the series so far.“I thought the last game we used the crowd’s energy incredibly well,” Ryan said. “I was in tight and I know Tuk [Rask] is really, really, really good at taking the bottom of the net away,” Ryan said of his winner, that came at the 5:43 mark of the overtime frame. Bobby Ryan proved the hero, redirecting a cross-ice feed from Kyle Turris on the power play, with the puck drifting past Boston goalie Tuukka Rask to give the Senators their second consecutive overtime win of the series, 4-3. At the other end, Rask was fortunate when a blast by Mike Hoffman, seeking his third goal of the game, rang off the iron.“Even though we fell down 3-0, we still battled back and showed some character,” Rask said. There is something troublesome about having a lead and trying to hold it in this opening NHL playoff tussle between the Ottawa Senators and Boston Bruins.But the only score that matters to both teams is the one on the scoreboard after the final whistle sounds and, in that regard, the Ottawa Senators are breathing a little easier. “And then [Monday night] I thought they did.