Bylsma said Crosby will be out at least a week because he has suffered a concussion and needs to be symptom-free for that long before he's cleared to play.
This is the first concussion Crosby has suffered since he entered the NHL.
Bylsma said prior to the game that the injury was suffered during Wednesday night's 8-1 win over the Tampa Bay Lightning and that it was not related to the head hit he took from Washington Capitals forward Dave Steckel just before the end of the second period of the Bridgestone NHL Winter Classic on New Year's Day.
Asked again after the game, Bylsma said Crosby's presence in the lineup Wednesday was proof he didn't get a concussion on New Year's Day.
"We wouldn't have thought he was OK to play," he said. "He certainly saw doctors."
Crosby took a hit from Tampa Bay defenseman Victor Hedman at 18:41 of the second period Wednesday night, one that earned Hedman a minor for boarding, but Bylsma would not confirm whether that was where Crosby got hurt.
Now, with games within the next seven days at home against Minnesota and Boston then back in Montreal, the Penguins need to learn to cope with life without their leader.
"We play 40 minutes a game without Sid on the ice," Bylsma said. "So we're comfortable with knowing how we need to play and how it needs to be. So we're going to keep playing the same way and finding a way to win hockey games."
Crosby flew to Montreal after the Tampa game, then flew back to Pittsburgh when he decided Thursday morning that he would be unable to play.
He's just the latest key player to go down for the Penguins this season -- Jordan Staal played his first game in the Winter Classic and Evgeni Malkin missed four games earlier this season -- but it hasn't stopped Pittsburgh from piling up the best record in the Eastern Conference.
Replacing Crosby, however, is a whole different story.
"We've had very few games with a full lineup," Bylsma said. "It's going to affect us in a lot of different areas, match-up wise, faceoff wise. He's a big part of our team. But the personality of our team is that we know how to play no matter who's in the lineup."
Crosby was not the only Penguin missing from Thursday night's lineup -- forward Matt Cooke joined him on the plane to Pittsburgh to attend to what Bylsma called "personal matters."