Stalock, who had made three previous appearances in relief of Antti Niemi, admitted he was nervous and excited for this one.
"I think it helped a lot being a five o'clock game for me and not having to sit around all night and come to the rink and go through the routine," he said. "It was a little easier than sitting around all day in my hotel room."
Stalock was solid throughout, including making 16 saves in the first period to help the Sharks jump out to a 3-1 lead.
"Maybe it's a good thing that I saw a lot early and was able to feel it," he said. "They were kind of shooting it from everywhere, which I was kind of expecting they would, but not being in a game yet I was lucky enough to make saves."
Stalock's teammates were happy to see him earn the win and were thrilled to give him a few early goals to help with his confidence.
"He's been patiently waiting behind (Niemi), and to come out with a performance like that was huge for us," captain Joe Thornton said.
The Sharks were outshot for the first time this season.
The Senators had few answers for their recent play, but they realize things have to change soon. For the second straight game, Ottawa fell behind 2-0.
"We can't spot good teams leads," Senators captain Jason Spezza said. "We get behind, and then it doesn't matter what we do. We're chasing the whole game."
The Senators' lack of urgency proved costly as the Sharks scored two early third-period goals to put the game out of reach.
Sheppard scored his first of the season when he beat Anderson far side. Pavelski made it 5-2 by putting in a big rebound.
Trailing 3-1 to start the second period, the Senators got within a goal when Methot fired in a shot from just inside the blue line.
Hertl opened the scoring just 1:16 in when the puck bounced over the stick of Senators defenseman Joe Corvo, allowing Hertl to quickly put a shot between Anderson's legs.
Just over five minutes later, sloppy play by the Senators in their end allowed Desjardins to make it 2-0. He picked up a rebound and scored off his backhand.
"I just thought we chased the game the whole night," Ottawa coach Paul MacLean said. "I'm very concerned about the way that we've played to this point in the season."
Ottawa cut the lead in half midway through the period when Karlsson scored through traffic. With forward Cory Conacher creating a screen, Stalock barely had a chance to see the shot until it was behind him.
Any momentum gained from the goal was lost after the Senators gave up a short-handed goal with less than two minutes remaining in the period.
"Our identity in the past has been a hard-working group that's very competitive and comes to play the whole game and plays hard the whole game," MacLean said. "Right now we don't do that. So what is our identity?"
Karlsson bobbled the puck at his blue line, and Logan Couture took off on a breakaway. Anderson made the initial save, but the puck rested in the crease. Wingels banged it in to restore the two-goal lead.
"Right now, we make a mistake and it ends up in our net," Anderson said. "I'm not sure how you change that. You need a little bit of luck, but at the same time you've got to limit the amount of mistakes you make."
Ottawa LW Clarke MacArthur missed the game with what the Senators described as a minor injury. LW Matt Kassian and D Eric Gryba were healthy scratches. ... San Jose is still without RW Brent Burns, who was struck in the mouth by a puck. RW Marty Havlat sat out because of a pelvis injury, and D Dan Boyle missed his sixth straight game. LW Matthew Nieto was a healthy scratch.
Copyright by STATS LLC and The Associated Press
OTTAWA, ON - OCTOBER 27: Andrew Desjardins #10 of the San Jose Sharks celebrates his first period goal with team...
(Photo by Jana Chytilova/Freestyle Photography/Getty Images)