Crosby, who has not resumed skating, is still doing light workouts, Bylsma told reporters.
The update was the first since Dec. 12, when Crosby said he had passed an ImPACT test -- designed to diagnose concussions -- but that he was dealing with a recurrence of symptoms and had decided to be cautious in returning. He was placed on the injured list on Dec. 17.
Krejci was digging for the puck in front of the Pittsburgh bench when Crosby closed in. The Boston forward spun just before Crosby arrived, with Krejci's left elbow appearing to knock Crosby off-balance as play continued. No penalty was called on the play and Crosby didn't miss a shift, playing more than 21 minutes.
A day after the game, Crosby developed a headache. While tests did not diagnose a concussion, he had not played since.
"The ImPACT (test) isn't everything. You've got to listen to your body on these things too," he said Dec. 12.
Crosby was originally injured in January when hits to the head in consecutive games caused a concussion. He was out of action from Jan. 5 until Nov. 21.
Crosby scored two goals in his season debut against the New York Islanders and collected 12 points in eight games before being re-injured.
Bylsma said defenseman Kris Letang, out since Nov. 26 with a concussion, is feeling better but his return date is unknown.
Information from The Associated Press was used in this report.