McAmmond's goal with a little more than four minutes remaining in regulation time was just his eighth of the season, but it capped a third-period
comeback and the Ottawa Senators went on to record their fourth straight victory with a 5-3 win.
McAmmond, whose job is to provide defensive responsibility to the high-scoring duo of Spezza and Heatley, took a pass from Spezza from behind the net and beat Atlanta goaltender Kari Lehtonen after the Senators had rallied from a 3-2 deficit.
"To play with those guys, I just try to do my part and get those guys the puck," McAmmond said. "Spezz had it and he made a great pass and I just tried to find that spot. That was a big game for us."
In a spirited, physical and chippy contest before a sold-out Scotiabank Place crowd of 19,881, the Senators (34-22-3) notched their first win in three games between the teams this season.
Mike Comrie had tied the game for the Senators with a goal earlier in the third period.
"It was a good hurdle for us to get over tonight, by showing that we could beat a physical, hard-hitting team," said Spezza, who was often on the receiving end of some extra attention from hulking Thrashers defenceman Andy Sutton.
Senators defenceman Andrej Meszaros and Thrashers left-winger Ilya Kovalchuk also had a running battle that culminated in both players heading for the bench after being shaken up by third-period hits.
"It was a pretty intense game," Spezza said. "It's playoff-type hockey."
Chris Kelly, who scored short-handed and had an assist, Peter Schaefer and Mike Fisher, into an empty net, had the other goals for Ottawa.
Spezza and Daniel Alfredsson finished with two assists apiece and Martin Gerber made 28 saves.
Senators coach Bryan Murray picked up career win No. 599. Only four coaches in NHL history have reached the 600-victory plateau.
Slava Kozlov scored once on the power play and added an assist for the Thrashers (30-22-9), who lost their fourth straight game and fell to 1-6-1 in
the past eight.
The goal was Kozlov's 20th of the season, the 10th time in his career he's scored at least 20.
Atlanta also received a power-play goal from Steve McCarthy and an even-strength marker from Glen Metropolit.
Marian Hossa had two assists against his former team and Lehtonen finished with 25 saves.
Thrashers left-winger Brad Larsen left the game in the second period and didn't return because of a lower-body injury. His status was not immediately
Atlanta went 2-for-3 on the power play; Ottawa was 0-for-2.
Kozlov had put the Thrashers into the lead late in the second period and Atlanta appeared to be on its way before the Senators rallied.
"We were pretty confident we could come back," Spezza said.
Comrie scored on a rebound midway through the final frame to set the stage for McAmmond.
"It's frustrating," said Hossa, who has eight points, all assists, in three games against the Senators this year. "I think we played a solid game on the road and just the last 10 minutes.
"They got that rebound goal (Comrie's) that got the ball rolling and we couldn't stop it."
Notes: The Senators scratched tough guy Brian McGrattan for the seventh straight game . . . Ottawa plays host to Edmonton on Tuesday . . . Emery is eligible to return Thursday versus Buffalo . . . Thrashers centre Steve Rucchin missed his fourth straight game with an upper-body injury. Left-winger Eric Boulton also didn't dress . . . Winger Denis Hamel faced the Senators for the first time since being claimed off waivers from Ottawa a week earlier . . . Atlanta wraps up its road trip Tuesday at Carolina.