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.
You don't see many. The [Drew] Doughtys, the [P.K.] Subbans, those are guys that create offense from the back and then on top of that ability, the size that he has. In the West you play against some pretty big players, and being able to clear the crease and contain the [Ryan] Getzlafs and the [Corey] Perrys and [Anze] Kopitars and players like that, we're excited about him going back there.
— Sharks general manager Doug Wilson on Brent Burns returning back to defense