TORONTO - The Toronto Maple Leafs didn't allow a goal through their first five periods of the season.
Suddenly, their strong defensive game unravelled in a hurry.
The Maple Leafs almost wasted a hat trick by Phil Kessel on Saturday, surviving a furious Ottawa comeback to hang on for a 6-5 victory over the Senators.
Up 5-1 midway through the third period, Toronto sat back and watched as Ottawa jumped into the game.
"I'm hoping it was all a dream and I'm going to go out there for the third period," said James Reimer, who had his shutout streak broken at 101:42. "But, you know what, a win's a win.
"It sure wasn't pretty, but the fans got their money's worth and we got the two points."
Mikhail Grabovski, Joffrey Lupul and Colton Orr also scored for Toronto (2-0-0). Reimer made 27 saves for the win.
Kessel added an assist, while Lupul had two of his own.
Daniel Alfredsson scored twice for the Senators (0-2-0). Colin Greening, Jason Spezza and Stephane Da Costa, with his first in the NHL, had the other goals for Ottawa. Erik Karlsson chipped in with three assists.
Alex Auld took the loss in relief for Ottawa after allowing two goals on 11 shots in relief in the third period. Craig Anderson started and gave up four goals on 20 shots through two periods.
"We played good for 50 minutes and took our foot off the pedal," said Maple Leafs' captain Dion Phaneuf, who has three points in two games. "We got to learn from that, but it's a big two points for our team and we'll take them."
After Greening and Orr exchanged goals to start the third period, Alfredsson made it a 5-2 game at 11:04 with a short-handed breakaway goal after taking a clearing attempt coming out of the penalty box.
Then the Leafs gave the Senators a 5-on-3 man advantage and Ottawa struck with a pair of power-play goals eight seconds apart. Spezza scored at 15:36 and Alfredsson got his second of the game on a neat deflection.
Kessel completed his hat trick at 17:41, snapping a shot over Auld's glove hand on a 2-on-1 rush, and the Leafs looked to have quelched the Senators' comeback attempt.
But Ottawa struck back when Da Costa took a feed from Karlsson and scored at 18:06 to set up a wild end to the period.
The Senators pulled Auld for an extra attacker but couldn't quite complete the comeback as the Air Canada Centre crowd breathed a huge sigh of relief at the final buzzer.
The Leafs' letdown overshadowed a four-point night by Kessel, who continues to evolve into a more complete player.
"He played really well the last two months of last season and he's continuing where he left off," said head coach Ron Wilson. "We've asked him to be a little more aggressive on the forecheck and he was doing that.
"Tonight he was getting in there really quick."
Wilson rewarded Kessel for his hard work by putting the winger out to protect the 6-5 lead in the last minute of the game.
According to Phaneuf, the Leafs' star sniper has been Toronto's top player up front so far for the team.
"Phil has been extremely good for us both games," Phaneuf said. "He's been one of our best forwards, if not our best.
"And not just scoring goals. He's been strong in both ends of the ice for us."
Ottawa came out strong to open the game, but it was Toronto that took a 2-0 lead into the first intermission on goals by Grabovski and Kessel.
The intensity between the provincial rivals picked up in the second period.
Phaneuf drew a crowd of Senators after he delivered a huge hit on Da Costa cutting into the middle of the ice, knocking his helmet off. Phaneuf wasn't assessed a penalty for the hit.
"That's one thing that bugs me," he said. "You make a clean hit and guys come in and expect you to fight.
"I don't have anything to prove to them. I'm going to play style that I play."
After the hit, Chris Neil went looking for retribution and gave Luke Schenn a beating in a one-sided fight.
"You don't like to see one of your teammates get hit like that," Neil said. "It was a pretty big hit for them."
Ottawa head coach Paul MacLean, however, saw no problem with the hit.
"You have to accept a certain amount of risk when you play this game," he said. "I know I'd never come across (the middle of the ice) like that.
"I thought the hit was clean and I expected no other response other than the one we had on the ice."
Neil got 19 minutes in penalties for starting the fight and the Leafs capitalized at 7:56 with another power-play goal.
John-Michael Liles' shot from the point was deflected past Anderson by Lupul.
Toronto took a 4-0 lead into the second intermission when Kessel scored his second of the game after taking a nifty pass from Tyler Bozak and deking around Anderson.
The Leafs' top line of Lupul, Bozak and Kessel finished with eight points.
Toronto went 2-for-9 with the man advantage, while Ottawa wound up 2-for-8.
Notes: The Senators lost their season opener 5-3 in Detroit on Friday. ... Orr took Jay Rosehill's spot in the lineup for Toronto. ... Ottawa plays back-to-back games 16 times this season. ... The Maple Leafs started the season tied for the second youngest roster (26.3) in the league behind the Nashville Predators. ... The Leafs have a week off until they play again when the Calgary Flames come to town next Saturday. The Senators return to Ottawa for their home opener Tuesday against the Minnesota Wild. ... Announced attendance was 19,324.