Defenseman Cam Fowler suffered a sprained right knee during the first period of the Ducks’ 4-2 victory Sunday over the Philadelphia Flyers at the Honda Center. The Ducks couldn’t say Monday how long he might be sidelined, however. They did say they expect to learn more about his layoff later in the week. He wasn’t immediately placed on IR, and wasn’t available for comment Monday.

“I think we all consider him one of our top defensemen,” Ducks coach Bruce Boudreau said before the team left Monday for a three-game trip to play the Calgary Flames, Edmonton Oilers and Vancouver Canucks. “You lose him for any length of time, and I don’t know what the time-frame is, it’s going to hurt.”

Fowler scored three goals and 12 points with a minus-11 defensive rating in 34 games before he was injured. He had an assist on Ryan Getzlaf’s power-play goal in the first period Sunday, but could not finish the game.

The Ducks recalled defenseman Shea Theodore from San Diego of the AHL.