The Bruins play at the Edmonton Oilers on Tuesday (9 p.m. ET; SNW, NESN, NHL.TV) and are scheduled to travel to Toronto on Wednesday. Holden will meet them there in advance of their game against the Toronto Maple Leafs on Saturday. It's not clear if he will play against the Maple Leafs.
Boston leads Toronto by three points for second place in the Atlantic Division.
The Bruins have been using Grzelcyk, a 24-year-old rookie, on the left side of their third pair with Adam McQuaid. Grzelcyk has 10 points (one goal, nine assist) in 39 games. He will play his 39th consecutive game Tuesday and he's averaging 15:50 of ice time per game.
"To his credit, to the credit of the team, to put him in there and [coach] Bruce [Cassidy] and [assistant] Kevin [Dean] to trust him, he's responded, he's a big part of our group," Sweeney said. "Nobody should be looking over their shoulder. Just realize how imperative it is to be a deep team. We've said it all along that we want to be a deeper, more talented team, and [Grzelcyk] is a big part of that."
Holden played 18:58 per game, including 2:03 on the penalty kill, for the Rangers. He played primarily in a top-pair role on his off side (the right side) with Ryan McDonagh this season.