The third time proved the charm for the Montreal Canadiens, who stumbled twice after taking a 3-0 lead in their Eastern Conference First Round series against the Ottawa Senators before winning in six games.

The Canadiens began the series with three straight one-goal wins, including two in overtime, yet failed in their first two attempts to eliminate the Senators, who went 23-4-4 over their final 31 regular-season games to qualify for the Stanley Cup Playoffs.

The Senators, who became the first NHL team to come back from 14 points out of a playoff berth to qualify, scored first in each of the first five games. The Canadiens finally took a 1-0 lead on Brendan Gallagher's first-period goal in Game 6. So, how did the Canadiens advance despite not holding a two-goal lead in the series until there was less than a second remaining in the clincher?

Here are five reasons the Canadiens advanced to the second round:

1. Carey Price -- A Vezina Trophy finalist and Hart Trophy candidate, Price was quietly, consistently and calmly stellar in the first four games, including a 1-0 loss in Game 4. Then he allowed five goals in a 5-1 loss as the Senators avoided elimination for a second game in a row.

The Senators may have thought Price was penetrable after they threw more traffic at him in Game 5 than you would see on the Decarie Expressway at rush hour, but he ultimately ended Ottawa's storybook run for the ages with a 43-save shutout in the clincher. Kyle Turris, Mika Zibanejad and Senators fans will replay Price's highlight-reel saves in their minds all summer.

"That's always the last worry on our mind, is the way Carey Price is going to play," left wing Max Pacioretty said. "Having a goalie like that is refreshing because you can focus on your game and never have to worry about what he's going to do. He shows up every game. He's the best competitor I've ever seen and it showed [Sunday]."

2. Tenacity -- The only time the Canadiens scored first was in Game 6, which proved timely considering that goal had to stand up for the win until the final second. The Canadiens came back to win the first three games, including Games 2 and 3 in overtime, chasing Andrew Hammond, the hottest goalie in the League entering the playoffs, in the process. Dale Weise scored twice on Craig Anderson in a 2-1 win to give the Canadiens a 3-0 series lead, then Anderson became the hottest goalie in the playoffs while leading the Senators to wins in the next two games. The Canadiens held tough, though, and made Gallagher's goal the only one they needed in Game 6 as Price bested Anderson to close out the series.

"This was a very dangerous team," Gallagher said. "They're a good hockey club. If you look at what they did the last half of the season, they would have given anyone a scare, and for us, we won close hockey games and I think that was the difference. We were able to bear down, and if it was a one-goal game we were able to find ways to win those hockey games. I guess it speaks to the character we have in the locker room, just the comfort zone that we've been in that situation enough that we trust that the guys are going to do the job."

3. Penalty killing -- This may seem odd, considering the Canadiens' 75-percent success rate during the series, but their successful penalty kills proved timely and they were a constant threat to score. Lars Eller's shorthanded goal split the impact and the momentum of the two goals the Senators scored on a five-minute power play midway through Game 1 after P.K. Subban got a major and game misconduct for slashing Mark Stone. Among other offensive opportunities produced by Canadiens penalty killers, Brandon Prust had a sensational shorthanded scoring chance on a breakaway in Game 4, which the Canadiens lost 1-0. Bolstered by Max Pacioretty's return to the lineup in Game 2, the Canadiens killed 10 of the Senators' 11 power-play opportunities in the four lowest-scoring games of the series.

"It's been a big factor all season long," Price said. "Our penalty killers do an excellent job of getting in lanes, they're willing to sacrifice their body and do whatever it takes to keep the puck out of the net."

4. Depth on defense -- The Canadiens began the playoffs with nine healthy defensemen. With his top three pairings set, coach Michel Therrien had veterans Sergei Gonchar and Mike Weaver as options to draw into the lineup, if necessary, as well as rookie Greg Pateryn, who played a solid 17 games after he was called up from Hamilton of the American Hockey League. When Nathan Beaulieu was injured in Game 3 and knocked out of the series, Therrien inserted Pateryn, who got his first NHL point with an assist in his second playoff game. His shot led to Brendan Gallagher's game-winning goal in the series clincher.

5. Marc Bergevin -- The Canadiens general manager, his trusted advisors and pro scouting staff all deserve a nod for providing Therrien with players acquired prior to the 2015 NHL Trade Deadline who made key contributions to the series win. Forwards Brian Flynn and Torrey Mitchell delivered crucial offensive contributions in Game 1, and Mitchell won 10 of 16 defensive zone faceoffs in the clincher. Forward Devante Smith-Pelly delivered 22 hits and Jeff Petry was the Canadiens' most consistent defenseman throughout the series.