PITTSBURGH -- The Ottawa Senators lost a lot more than a game.
Star defenseman Erik Karlsson went down with a left Achilles injury when he was cut by a skate blade late in the second period in the Senators' 4-2 loss to Pittsburgh on Wednesday night.
"It's a tough blow," Senators captain Daniel Alfredsson said. "Obviously, the way he's playing and how much he means to our team, it feels terrible and I feel really bad for him."
The Norris Trophy winner last season as the NHL's top defenseman, Karlsson was cut by Penguins forward Matt Cooke's skate blade as the two tangled along the boards. The Senators said Karlsson will need surgery.
"We all know who's involved in it," Ottawa coach Paul MacLean said about Cooke. "That's just the way it is. The injury to Erik was unfortunate and it happens on a nothing play that could've potentially been whistled down."
Cooke has been suspended several times for much criticized hits, some of them involving head-shots that injured opposing players. In 2011, Cooke was suspended for the Penguins' final 10 regular-season games and the first round of the playoffs after an elbow to the head of New York Rangers' defenseman Ryan McDonagh.
Karlsson fell to the ice and was in visible pain after tangling with Cooke. He needed help getting back to the bench and displayed frustration, throwing his stick against the boards before disappearing down the runway.
"Him and I were engaged and he went down screaming," Cooke said. "I didn't even know what happened. It's a complete accident and obviously I feel terrible about it. It has happened a few times over the past couple years and it's scary."
The Senators stood up for their teammate in the third as Chris Neil took penalties for roughing and a 10-minute misconduct after tussling with Cooke.
"I think at the end of the day you kind of expect it," Penguins star Sidney Crosby said. "I don't think anyone was shocked to see Neil go after him, but unfortunately that's kind of how it works sometimes."
James Neal scored twice, and Crosby had a goal and two assists to help Penguins snap a two-game losing streak and pull within a point of Eastern Conference-leading New Jersey. The Devils swept Pittsburgh in a home-and-home series over the weekend.
"We had two tough games against New Jersey and after those two losses we wanted to have a good bounce-back game and we did that tonight," Neal said.
The loss of the Karlsson is a major blow for the Senators, already playing without center Jason Spezza and left wing Milan Michalek. Spezza is out indefinitely after surgery for a herniated disk, and Michalek was a late scratch Wednesday because of a lower-body injury.
"He's a player who is irreplaceable," Senators goalie Craig Anderson said. "It's unfortunate, but there are no words that can explain what we're feeling."
Ottawa, behind Anderson's 42-save effort, shut out Buffalo on Tuesday night at home, but couldn't carry the momentum to Pittsburgh. Anderson stopped 25 shots Wednesday.
Both goalies were strong early as the teams combined for 26 first-period shots. The Penguins scored the lone goal of the opening period, the 11th time in 14 games Pittsburgh scored first.
Dupuis one-timed his fifth of the season behind Anderson with 3:37 left in the period, taking a cross-ice feed from Crosby, who set up the goal after pouncing on Chris Neil's turnover at the blue line.
The Senators took the lead with goals scored 24 seconds apart.
The first came just as a two-man advantage expired as Da Costa, from behind the net, banked a shot off the back of Fleury's pads that trickled across the goal line.
O'Brien gave the Senators the lead 24 seconds later with a wrist shot from the faceoff dot that caromed off Fleury's glove and bounced into the net.
"I was not happy with giving up two so quick, but I knew if I made some key saves for the guys, they would get them back," Fleury said.
And that's exactly what happened.
Neal tied it less than 3 minutes later with his NHL-leading sixth power-play goal, the sixth straight game the Penguins scored with the man advantage. Crosby recorded his 400th career assist on the goal, sending a pass from the corner to Neal, who unleashed a wrist shot over Anderson's shoulder from the faceoff dot.
Neal gave the Penguins the lead for good 1:52 into the third period, tapping the rebound from Deryk Engelland's shot from the point past a sprawled Anderson.
"I've often said if you're going to make a book on a shooter and a guy getting open, just watch (Neal) play the game," Penguins coach Dan Bylsma said. "He has an elite release when he gets the opportunity."
Crosby's sixth of the season, coming seconds after a Senators' penalty expired, put the Penguins ahead by two goals midway through the third.
The Penguins traded LW Eric Tangradi to Winnipeg for a seventh-round draft pick Wednesday. ... C Dustin Jeffrey and D Robert Bortuzzo were scratched for Pittsburgh. ... Penguins C Brandon Sutter appeared in his 300th career game. ... Ottawa continues a three-game trip, visiting Toronto on Saturday night, while the Penguins open a two-game road swing Friday night at Winnipeg.