"I made history? I played three shifts, and I got a star?" said Dagenais, who had no interest in recovering the historic puck as a keepsake.
Theodore, who stopped Kovalchuk on a breakaway in overtime, made a glove save on Hossa on Atlanta's third attempt. The sellout crowd cheered as the Canadiens goalie held his glove hand up ahead of the goal line while sprawling back into the net.
"I was confident," Theodore said. "They are players who like to shoot."
Shields acknowledged that his counterpart played well, though he wished his talented snipers would have taken a different approach in the shootout.
"I didn't like the way we shot the puck," the Thrashers goalie said. "To be honest with you, I thought the guys should have shot higher. Every shot at team practice is high, I don't know why those weren't!"
Theodore drew a roar 3:27 into overtime and heard chants of "Theo! Theo! Theo!" when he turned away a clear breakaway by Kovalchuk, who scored his 15th goal in the second period.
"He played well all night. He looked like he was moving quick," Thrashers captain Scott Mellanby said. "He made a real quick save on me as well in the third period. I thought I'd taken a step to get around him and a scramble happened and he saw his reflex as he kicked out and got a toe on it."
Kovalchuk has 14 goals and 13 assists in 14 games since scoring once in his first four games.
The Thrashers outshot Montreal 38-30, including 14-8 in the third.
Bondra also scored for Atlanta, which tied the game twice in the second.
Ryder scored his team-leading 10th goal to make it 1-0 early in the second on the first of the Canadiens' two power-play goals. Ryder also assisted on Andrei Markov's goal later in the period.
Theodore, bothered lately by a groin injury, stopped 36 shots in regulation, including 14 in the third. Shields made 28 saves overall.
Atlanta went 0-for-13 on the power play, including five opportunities in the first period. The Thrashers also had five power plays in the third, including one with 3:35 remaining when Montreal defenseman Mike Komisarek was penalized for hooking.
"Luckily, our penalty killing was outstanding," Canadiens defenseman Craig Rivet said. "Jose was rock solid in there, no rebounds at all. He saw a lot of the pucks and made some great saves. The guys in front of him, our forwards to our (defense), did a really, really solid job against a very good power play."
Ryder opened the scoring 1:36 into the second with the first of two Montreal power-play goals in the period. Ryder got his team-leading 10th goal when he drove a loose puck off a scramble past Shields into a wide-open right side.
Kovalchuk tied it at 5:43. The speedy Russian winger received countryman Slava Kozlov's pass and drove in on Theodore, flipping a shot over the Canadiens goalie's pad to even it at 1.
Montreal had a great opportunity to take the lead again midway through the period when Rivet hit the left post shortly after he came out of the penalty box.
Another Canadiens defenseman made the most of his chance on another power play later in the period as Markov drove a slap shot past Shields from the left point to make it 2-1 at 15:35, just five seconds after Montreal had a 5-on-3 advantage for 25 seconds.
Bondra drew the Thrashers even again, and this time it took just 24 seconds.
The unassisted effort occurred when Canadiens forward Radek Bonk's backhand clearing attempt was intercepted by Bondra, who fired a quick shot past Theodore at 15:59.
- Thrashers C Marc Savard ended a six-game point streak. Savard, who has 23 assists this season, had one goal and 14 assists during the run.
- Canadiens D Sheldon Souray didn't play because of a groin injury. He is day to day.
- Montreal hasn't scored on a 5-on-3 advantage this season.
- The Canadiens have sold out each of their 13 home games this season.