There’s hardly been a point all season where the Bruins have had consistent, reliable line combinations. One of the times they did was when the top unit of Brad Marchand, David Pastrnak, and Patrice Bergeron was playing like the top trio in the league.

Something remarkable had to happen to consider splitting them up upon Bergeron’s return.

David Krejci’s play between the two top wingers has been that remarkable.

On Friday, Bergeron, sidelined for the last 16 games with a collarbone injury, practiced between Marchand and Danton Heinen while Krejci was with Pastrnak and Joakim Nordstrom.

Boston hosts Nashville today at 1 p.m.

Bruins head coach Bruce Cassidy said after the victory over Anaheim on Thursday night that the Bruins might alternate pairs on their top two lines, keeping Marchand and Bergeron together and Pastrnak with Krejci. If things stay the way they did in practice on Friday, it would appear that’s where things are going.

At least, to use Cassidy’s words, that’s how it will start.

“We looked at it today,” said Cassidy. “Bergy will be a game time decision. If he wakes up tomorrow and feels good from today’s practice, then he’s in. If he’s in, then that’s the direction we’re going to go when (Jake) DeBrusk will not be in.”

Krejci has built chemistry with the forwards he’s played with, especially Pastrnak, proving to be effective when he has strong wingers to his left and right.

“There’s a domino effect, obviously,” said Cassidy. “With Nordy going out, so it’s (Colby) Cave, (David) Backes and (Sean Kuraly). We threw some things together today. It will be a decision we talk about a little tomorrow.”

Even before Bergeron was injured, the Bruins were tempted at times to place Pastrnak with Krejci to spread balance throughout the lineup. The top trio continued to be so productive, it was tough to imagine them not being together all season when healthy.

Seeing how often the Bruins flip their lines around, especially when young players like Heinen are involved, how long their starting lineup is what they stick with remains to be seen.