Nylander could be an option for Game 4.

The Toronto Maple Leafs have been without star forward William Nylander for three crucial games against the Boston Bruins in their Eastern Conference first-round series — and the hockey world might now know the reason why.

Nylander is reportedly suffering from a severe migraine, Sportsnet’s Elliotte Friedman confirmed on Thursday.

“According to multiple sources, William Nylander’s absence from the Toronto lineup has to do with a migraine so severe that team doctors tested to see if he suffered a concussion,” the hockey insider explained. “One of the reasons for the secrecy around his situation is that an actual diagnosis has been hard to come by, whether it is a migraine, a concussion or something else that could affect that area.

“That secrecy led to wild speculation — even by Toronto standards — as to why Nylander missed the first three games of the Boston series. It’s believed Nylander first indicated an issue Thursday, the day after the Maple Leafs ended their regular season in Tampa Bay. He played all 82 games in 2023-24.”

After not missing a single game during the regular-season — and scoring a career-high 98 points in the process — Nylander has been sorely missed for the team’s first three playoff games in 2024. But the hope around Toronto is that Nylander will be ready to return to the lineup for a critical Game 4 at Scotiabank Arena on Saturday.

Leafs could really use William Nylander in Game 4

Kim Klement Neitzel-USA TODAY Sports

“In September 2022, Nylander told reporters he switched to a tinted visor because of migraines he’d suffered the previous season,” Friedman continued, adding, “There is hope he will play Game 4, with Boston leading the series 2-1.”

Bobby McMann, who hasn’t played since suffering a lower-body injury against the Detroit Red Wings at the end of the regular-season, also hasn’t been ruled out but he isn’t expected to play on Saturday, per Friedman.

Nylander has been durable throughout his career, and Game 1 was just the second time he’s been forced out of a playoff game due to injury — and the first since November of 2016.

The Swede has scored 17 goals and 40 points in 50 career postseason contests; he was especially good last playoffs, scoring four goals and 11 points over 10 games as Toronto beat Tampa Bay in Round 1 before bowing out to the Florida Panthers in five games.

The 27-year-old is being sorely missed a year later — Toronto scored just a single goal in Game 1, and only two in Game 3. That’s not going to be enough to win the series, especially if the B’s turn back to Jeremy Swayman on Saturday.

Swayman has been lights out against the Leafs this year, and that trend continued on Wednesday. With an opportunity to take back home-ice advantage, the Leafs were instead stymied by the goaltender in front of the home crowd.

One thing is for sure: Toronto is a completely different team with William Nylander in the lineup. And they’re going to need him if they hope to beat the Bruins in a Stanley Cup Playoff series for the first time since 1959.