Puljujarvi extended the lead to 3-1 at 17:37, receiving a stretch pass from McDavid and scoring on a breakaway, and Devin Shore shot into an empty net at 18:21 for the 4-1 final.
"I thought we did a good job of taking [McDavid's] time and space early on," Petry said. "That last 10 minutes they were able to tie the game and then their momentum took over. I think that's where down the stretch games are going to be tight and whether we're up a goal or down a goal, we have to make sure we're mature in our game and not shy away from it. They gained momentum from that goal and they kept rolling from there."
Edmonton outshot Montreal 19-8 in the third period.
"I liked that we got better as the game went on because we weren't very good early," Oilers coach Dave Tippett said. "We got a lot better. The third period was a strong period for us, we kept the pressure on them and capitalized on some chances. But early in the game, we just weren't real crisp with the puck, we needed to get our feet going a little better. But as the game went on we got better and we found a way to win."
Staal gave the Canadiens a 1-0 lead at 6:46 of the second period when Corey Perry's cross-ice pass went in off his skate.
"With five minutes to go, McDavid gets the puck and speeds up," Ducharme said. "I think overall, we played two pretty solid periods; we can say 50 minutes. At one point we were good containing those guys, but he's probably the best player in the world now and he made the difference with five minutes to go."
NOTE:Oilers forward Jujhar Khaira left the game at 8:18 of the first period after taking a hit from Canadiens defenseman Alexander Romanov along the boards.