It could happen at a moment’s notice, as part of a plan or maybe not at all.

If the Bruins use a goalie besides Jaroslav Halak during their playoff run, though, Dan Vladar will get the call. And should that come to pass, Vladar will play in the NHL for the first time in his four-year pro career, as well as for the first time since March 11, when he won his seventh game in a row at AHL Providence.

“Right now, [Vladar] is” the Bruins’ No. 2 goalie, said coach Bruce Cassidy, basing some of his decision on the recommendation of goaltending coach Bob Essensa and the organization’s goalie development coach, Mike Dunham, and some on Vladar’s performance: He was the AHL leader in goals-against average (1.79) and saves percentage (.936).

The potential for Vladar to make his NHL debut this postseason increased Saturday when No. 1 goalie Tuukka Rask left the Eastern Conference bubble in Toronto to be with his family. WEEI radio’s Greg Hill reported Wednesday that Rask had told him during phone conversations this week that one of Rask’s three daughters had experienced a “medical emergency; B’s general manager Don Sweeney [Saturday], and Cassidy, who exchanged text messages with Rask on Sunday, said Rask’s wife and three daughters were all healthy.”

Rask’s departure made Halak the No. 1 goalie, with Vladar and Max Lagace candidates for the backup position. Lagace, who played 17 NHL games with the Golden Knights (16 in 2017-18) before signing with the B’s as a free agent last summer, has no NHL postseason experience.

“We’ve got to go on the assumption that [Vladar] is a little ahead of [Lagace],” Cassidy said. “At the end of the day, it’s an unknown, no matter which one we put in.”

Vladar, who turns 23 Thursday, was drafted in 2015 (Round 3, No. 75 overall) and spent the bulk of his first two pro seasons in the East Coast Hockey League.

He moved up to Providence on a full-time basis in 2018-19 (31 games, 13-13-4 record, 2.73, .898), and shook off an injury that cost him six weeks early this past season to rise to the top of the AHL charts.

Cassidy’s concern with both Vladar and Lagace (22-7-3, 2.37, .919) is that neither goalie has seen any game action in more than five months.

Neither one played in the July 30 exhibition against the Blue Jackets, or in any of the Bruins’ three round-robin games because the B’s were preparing Rask and Halak for the playoffs.

“We watch in practice, obviously,” Cassidy said, “but having guys coming down and ripping shots in practice is not always a [good] judgement on how a goalie is going to play in a game.”

Cassidy said, however, that Vladar — who dressed as a backup for the fourth time on Wednesday for Game 5 of the Bruins’ first-round series against the Hurricanes — had looked good at tracking and handling pucks during practices, and that the Bruins’ strong defensive structure helps every goalie: Rask and Halak shared the William Jennings Trophy this season, combining to surrender the fewest goals in the NHL before the COVID-19 pandemic forced the suspension of the regular season on March 12.

“We’re not asking our goaltenders very often to go in there and stand on their head and win us hockey games,” Cassidy said. “We ask them to give us a chance to win every night.

“You need some stellar performances from time to time but we don’t feel we’re the team that needs it every night. That’s good news for both those guys.”

Around the boards

Zdeno Chara played his 145th career playoff game for the Bruins, tying Wayne Cashman for second on the team’s all-time list. Ray Bourque is No. 1, with 180. ... Winger Anders Bjork and defenseman Brandon Carlo entered Game 5 as the only Bruins who had played all seven games in Toronto (three round robin, four playoff) without scoring a point.

Defenseman Matt Grzelcyk, who was given a “maintenance game off” during the round robin, was also looking for his first point. ... Cassidy coached his 50th playoff game for the Bruins on Wednesday. He entered with a 25-24 record.