The 19-year-old was selected by Dallas in the first round (No. 23) of the 2021 NHL Draft.
"I'm so happy for him," Seguin said. "I told him before the game that I scored my first goal in my second game and he's got to try to one-up me."
Johansen redirected Eeli Tolvanen's shot at 4:53 for the 4-1 final.
"I played with 'Tolvy' all last year," Johansen said. "Love the kid. He's a horse. He's a little pit bull. He does a lot of good things out there. He earns everything he gets. I know what to expect from him. I thought he played a solid game."
NOTES: Marchment became the seventh player in Stars/Minnesota North Stars history to score multiple goals in his debut. The last player to accomplish the feat was Jaromir Jagr (two goals, Jan. 19, 2013). ... Johnston (19 years, 151 days) became the second-youngest player in Stars/North Stars history to score in his NHL debut. Dave Archibald (18 years, 179 days) scored twice for Minnesota on Oct. 10, 1987. ... Predators forward Cody Glass did not play due to illness and is day to day. … The Predators were playing their first game in North America after defeating the San Jose Sharks twice in the NHL Global Series in Prague to open the regular season. ... Dallas is the third team in NHL history with at least one goal by a teenager (Johnston) and one by a player age 38 or older (Pavelski) in a season opener, joining the Quebec Nordiques (Mats Sundin and Guy Lafleur, Oct. 4, 1990) and Florida Panthers (Jonathan Huberdeau and Alex Kovalev, Jan. 19, 2013).