By Vince Comunale
PITTSBURGH -- The Ottawa Senators lost 4-2 in Pittsburgh on Wednesday, but the loss could be even more costly as they also lost Norris Trophy winner Erik Karlsson indefinitely.
Karlsson sustained a laceration to his left Achilles tendon and will require surgery.
The Penguins, meanwhile, were pushed to victory by three-point efforts from James Neal and Sidney Crosby.
The Penguins broke the stalemate when Pascal Dupuis swept Crosby's pass into the net past a sprawling Craig Anderson for his fifth goal of the season at 16:23 of the first.
In the second, the Senators evened the game and then took the lead within 24 seconds.
The first of those goals came at 10:31 when Stephane Da Costa got his first of the season by banking a rebound off the backside of Marc-Andre Fleury.
Ottawa's second goal came off the stick of Jim O'Brien when he fired a hard wrist shot that handcuffed Fleury, deflecting off his glove and into the net. It was O'Brien's fourth of the season.
The Penguins tied the game, 2-2, on a power play goal at 13:47 of the second when a wide-open James Neal took Crosby's pass and wristed in his ninth of the season over Anderson's glove.
Crosby recorded his 400th career assist on the goal and it also marked the sixth consecutive game in which the Penguins recorded a power play goal.
The Penguins retook the lead 1:52 into the third when Neal tapped in his second of the game from right on the doorstep.
Crosby notched his sixth of the season at 11:42 of the third as the result of some brilliant passing just as a Penguins power play had expired.
NOTES: Before the game, Pittsburgh traded winger Eric Tangradi to Winnipeg for a seventh-round pick in the 2013 NHL Draft. In parts of four seasons with the Penguins, Tangradi recorded one goal and four assists in 45 games. ... G Craig Anderson has started all but two of Ottawa's 14 games. ... Pittsburgh C Brandon Sutter appeared in his 300th NHL game. ... Ottawa completed its third set of eight back-to-back games. ... C Dustin Jeffrey and D Robert Bortuzzo were healthy scratches for Pittsburgh. LW Milan Michalek (lower body) was scratched for Ottawa. ... Pittsburgh next plays at Winnipeg on Friday night, while Ottawa will travel to Toronto on Saturday.