Lehtonen lost his helmet as he fell back into the goal after the hard hit.
"Obviously not good," Star coach Lindy Ruff said after Dallas' 4-3 win. "Likelihood, it's a concussion."
In Lehtonen's place, Tim Thomas made his Stars debut and stopped all six shots he faced. They acquired him from the Florida Panthers in a trade at Wednesday's deadline. Minnesota was leading 3-2 at the time.
Haula received 15 minutes in penalties, a major for charging plus a game misconduct.
Yeah, it was a pretty special moment for me. Today was my Dad's [55th] birthday. I have a lot of family in town, so it was a special moment for me to score my first one today. A win definitely would have capped it off, but you can't have everything.
— Sabres rookie Jack Eichel after scoring a goal in his National Hockey League debut
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