Daniel Alfredsson got Ottawa even 1-1 by scoring a short-handed goal with 29 seconds left in regulation just after the Senators pulled goalie Craig Anderson for an extra skater.
“We were just calm,” Anderson said of the Senators’ mood heading into overtime. “We had tied it up. We had momentum. We felt like the fans really rallied behind us.
“Going into overtime, we knew we just had to build off the momentum and keep the pressure on.”
Anderson made 49 saves, including 18 after regulation. Tomas Vokoun stopped 46 shots for Pittsburgh and took his first loss (4-1) since taking over for No. 1 Penguins goalie Marc-Andre Fleury.
Game 4 of the Eastern Conference semifinal series will be in Ottawa on Wednesday.
Tyler Kennedy scored with just over a minute to play in the second period to give the Penguins a 1-0 lead. That stood up until Alfredsson tied it in the closing seconds of the third.
“Just praying that we get something to the net,” Anderson said of the tying goal. “We practice that drill all the time in practice. Guy drops it off and goes to the net.
“It was just the way we practiced. Alfie is one of the best guys in the game. We want the puck on his stick at all times.”
Ottawa forward Jason Spezza, who hadn’t played since Jan. 27 — after undergoing back surgery to repair a herniated disc — lined up alongside Milan Michalek and Cory Conacher.
The sellout crowd chanted the 29-year-old Spezza’s name during his first shift.
Spezza faced a familiar opponent. His last game before surgery was at home against the Penguins, when he earned one assist and logged 21 minutes of ice time.
In his first game back, Spezza was slow to backcheck but he managed to generate a few scoring chances and made nice passes.
His back was put to the test in overtime when Penguins forward Craig Adams delivered a bone-crunching hit along the boards. Spezza shook off the check.
Both teams had good scoring chances in the extra periods. Pittsburgh’s best scoring opportunity came when Pascal Dupuis hit the post with a drive during the first overtime.
Anderson was on his game after being pulled in Game 2. He robbed Penguins captain Sidney Crosby early in the second period, and moments later stopped a hard shot by Evgeni Malkin, who smashed his stick against the ice in frustration.
He again stymied Malkin with a sprawling save in the first overtime. Anderson’s effort brought the crowd of 20,500 to its feet with chants of “Andy! Andy!”
“You just want to give your team a chance to win,” Anderson said. “Sometimes stats are misleading. You just kind of build off the good stuff.”
The Senators took seven penalties against the Penguins, who own the top power-play unit in the playoffs, but didn’t allow a goal.
Senators defenseman Erik Karlsson took a slashing penalty with less than two minutes left in the game, but Ottawa killed it.
Ottawa improved to 3-0 at home in this postseason (3-0).