Brenden Morrow added his first playoff goal in more than five years, Tomas Vokoun made 19 saves and the Penguins rode their superstar captain to their fourth straight victory.
Crosby beat Craig Anderson three times in the game's first 22 minutes, sending the goalie to the bench after stopping 18 of 21 shots.
Kyle Turris, Colin Greening and Jean-Gabriel Pageau scored for the Senators, but couldn't stop Ottawa from falling into a deep hole against the Eastern Conference's top seed. The Senators have never won a playoff series after dropping the first two games.
I'm very excited about what happened today. We've worked on this deal with Toronto for a month, or over a month. It got a little bit of legs on draft day, but it really heated up last night, and we were able to complete the deal today.
— Penguins GM Jim Rutherford on Phil Kessel, who he acquired from the Maple Leafs in a trade on Wednesday