OTTAWA -- Dany Heatley's return to Ottawa gave the NHL a hostile homecoming of its own.
Antti Niemi made 28 saves for his first shutout of the season -- and San Jose's first, too.
Patrick Marleau and Justin Braun scored power-play goals on the Sharks' first two chances.
Heatley, who drew both Ottawa hooking penalties that led to San Jose's first two goals, was booed constantly as he played his first game at Scotiabank Place since leaving the team before last season.
"It definitely gets the adrenaline going a little bit more, not only for me but I thought for both teams out there, especially early," Heatley said. "It was kind of a playoff atmosphere in there and I thought the pace was really good to start the game."
Couture scored the Sharks' third and fourth goals in the first half of the third.
Pascal Leclaire stopped 29 shots for Ottawa, which has lost seven of nine, including a 4-3 loss to Edmonton on Tuesday night.
On the same night that NBA superstar LeBron James was enduring the vitriol of his former fans in his return to Cleveland, Heatley was subjected to the scorn of his one-time admirers in the Canadian capital.
A two-time 50-goal scorer with the Senators, Heatley was booed loudly throughout his shifts in the first period, prompting chants of "Traitor! Traitor!"
"He was a rallying point for our team tonight," Sharks coach Todd McLellan said. "Players elevated their play for him and they wanted to get it done, and that's a real good sign for us."
A Heatley No. 15 Senators jersey was tossed onto the ice during a stop in play early in the game but the Ottawa fans' wrath later dwindled to jeering their former star only when he touched the puck.
"I thought they did everything they could to help us out," Senators captain Daniel Alfredsson said. "They were really fired up. There was a great energy in the building. I think everybody expected the boos and the chants and I thought they handling it pretty classy. I didn't hear any really bad words."
Marleau put away a rebound for his 11th goal 12:49 in after Heatley drew a hooking penalty against Sergei Gonchar.
The crowd of 18,017 found something to cheer about when Heatley was called for high-sticking former linemate Jason Spezza 4:45 into the second.
The joy was short-lived.
Leclaire stopped Scott Nichol on a short-handed breakaway moments later.
Heatley then drew another hooking call right after he came out of the penalty box. He skated across the ice and got behind the Ottawa skaters to take a puck along the boards before driving the net, where he was tied up by Nick Foligno.
Braun got his first NHL goal when he beat Leclaire with a wrist shot from the point at 8:22 after taking a pass from Heatley.
"He came to play tonight," Braun said after posing for photos with his milestone goal puck. "He does every night but he had a little extra jump and drew a couple of great penalties, and that's what he can do."
Couture scored 35 seconds into the third and added his second straight goal at 6:14.
The crowd was warned about a potential delay-of-game penalty after more items -- apparently Senators merchandise -- were thrown onto the rink early in the third.
"It was weird," said Sharks forward Ryan Clowe, who added that he dodged a full can of beer thrown toward the San Jose players along with some plastic water bottles after the final whistle. "I don't know if I've ever seen jerseys thrown on the ice before like that. They just started to flood down and you know what it's like, once someone sees one person throw it, they all want to throw their jerseys."
Heatley first faced the Senators in a 5-2 win in San Jose on Dec. 1, 2009. He had 180 goals and 182 assists in four seasons with Ottawa from 2005-09. ... Senators defensemen Brian Lee and David Hale didn't play.