New Jersey general manager Tom Fitzgerald said Hischier is week to week.
The Devils are scheduled to begin on-ice training Friday, with Hischier participating in off-ice work. New Jersey is scheduled to open the season against the Boston Bruins at Prudential Center on Jan. 14.
"I'll do what I can with the training staff to be ready for Game One,' Hischier said Thursday. "Obviously, working out all these months and skating, it kind of happened at a bad time, but [it] could be worse too. It's nothing serious so [I] didn't need surgery, so I'm trying to stay positive and do what I can do to be ready for Game One.
The forward said he was injured earlier this month during an on-ice session earlier this month.
"I was practicing with guys on the ice and somebody fell on my foot," Hischier said. "I'm feeling a lot better right now already ... so it'll be week to week."
Hischier, who turns 22 on Jan. 4, was the No. 1 pick by New Jersey in the 2017 NHL Draft. He signed a seven-year, $50.75 million contract on Oct. 18, 2019 that begins this season.
In three NHL seasons, Hischier has scored 135 points (51 goals, 84 assists) in 209 regular-season games and has one assist in five Stanley Cup Playoff games.
He scored 36 points (14 goals, 22 assists) in 58 games last season and played in his first NHL All-Star Game. Hischier tied for first on the Devils with 42 takeaways (Blake Coleman, Jack Hughes) and was second with a 51.7 percent face-off winning percentage (507-for-980). He was second among Devils forwards in average ice time (18:04); Taylor Hall was first (19:11 in 30 games).
The Devils, who failed to qualify for the playoffs the past two seasons and seven of the past eight, were 28-29-12 (.493 points percentage) last season and were not among the 24 teams to compete in the Stanley Cup Qualifiers.
