New NHL rules change coach's challenge and face-off procedure

The NHL hockey season is underway, and fans can expect to see a few rule changes in action.

The big picture: The tweaks to the game were unanimously approved by the league's board of governors, general managers and player's association.

Here's a breakdown of the main changes:

Delay-of-game challenges

Coaches can now challenge the delay of game penalties.

Why it matters: Delay of game is called when a player in the defensive zone clears the puck over the glass and out of play — but it's not a penalty if the puck hits the glass first, something refs may miss.

• A failed challenge may result in an additional penalty against the challenging team.

No changes on a dislodged net

The defending team cannot make a line change if the goalie accidentally dislodges the net.

Flashback: The rule previously applied only to other players on the defending team.

Goalies get warm-up time

If an injured goaltender is removed from a game, their replacement may be given time to warm up.

• This time did not exist prior to this change.

Face-off tweaks

A change to rule 76.4 states that, after an icing call, the offensive center can now receive one warning for a face-off violation. A second violation will result in a bench minor penalty.

• Icing is called when a defending player clears the puck past the other team's goal line from their own zone. It's not called during a penalty kill.

No players on boards

The referee will warn players sitting on the boards (the walls along the rink) with their skate exposed during line changes. Skates must remain on the bench side.

• After one warning, the team will be given a bench minor penalty.