Rickard Rakell got a late power-play goal to force extra time, but Brady Tkachuk netted the winner just 25 seconds in on a goal that Casey DeSmith was especially displeased about letting in.
"Except for the last one, I thought I played well. The last one was not good," he said. "It went through me, kind of snuck through my armpit."
Much of the game was spent on special teams, and it was a particularly tough night for Pittsburgh's penalty kill, which has been pretty solid overall for most of this season.
To be fair, a lot was asked of that group, as Jeff Carter and Bryan Rust were both assessed four-minute penalties at different points in the game. Overall, the Penguins spent 15:26 of this contest shorthanded, and the Senators went 4-for-9 overall on the night.
"Well, we battled hard, but we didn't get it done," head coach Mike Sullivan said. "We gave up four goals against. It's not good enough. We battled hard. But when you spend a third of the game trying to kill penalties, it puts an awful lot of burden on those guys."
After Jason Zucker took a penalty 45 seconds into play, the Penguins winger opened the scoring at the 6:36 mark. Shortly after that, Carter took his double minor for high sticking - and the Senators converted both to go up 2-1.
"It starts with me on shift two, and it just carried through," Zucker said. "We've got to be better at staying out of the box and not putting our PK in that tough of a spot."
The Penguins did respond the right way, with Evgeni Malkin getting boarded and then tripped to give his team a 5-on-3 power play for just over a minute. He made the Senators pay, tying it up with his 16th of the season.
Mark Friedman then put the Penguins in front with his first of the year coming out of the first intermission, but after that, Pittsburgh's shorthanded woes continued. Ottawa tied it up with their third power-play goal of the night over halfway into the middle frame, and Rust took his double minor in the final minute.
The Penguins did kill that one off, but with 12 seconds remaining on a cross-checking call to P.O Joseph, the Senators took the lead.
"I think we gave them too much time today," defenseman Marcus Pettersson said. "When our kill is good, we pressure the puck all the time. We don't give them enough time to make plays and stuff like that. So, I think they were moving it pretty quick, but we can do a better job pressuring the puck.
Not to be outdone, Pittsburgh's power play went 2-for-5 on the night, with Rakell's goal at the 12:33 mark of the third essentially earning the Penguins that point.
"It's pretty tough to assess a game like that when half the game is special teams," Sullivan said. "There was no flow, there was no 5-on-5."
The Penguins will have a chance for redemption against this same opponent when they host the Senators for the second half of this home-and-home set on Friday at PPG Paints Arena.
