Tkachuk appeared in discomfort and waved his trainer over at 10:16 left in the third period after taking a shot attempt that made him skate directly to the bench shaking his head and unable to play.
He remained on the bench as he attempted to work through the injury but it became too much and he was shut down for the remainder of the game.
Losing Tkachuk will be a big blow to the United States if he is to miss some time as this is a shortened tournament and they have punched their ticket to the finals which will take place in Boston MA on Thursday February 20th.
Tonight's game against Team Canada was an explosive start as both Matthew and his brother Brady decided to ignite the Bell Center with two fights back-to-back within the first few seconds of the game.
Matthew took on Team Canada forward and Tampa Bay Lightning Brandon Hagel with Brady taking on his brother's teammate in Florida Sam Bennett.
Shortly after Team USA J.T. Miller decided he wanted to join in on the festivities and took on Canadian defenseman Colton Parayko Which had all fans on their feet and getting everyone energized.
With last night's loss, the Canadians will now face Finland in an attempt to punch their ticket into the finals to face off against the United States.
Canada will have an opportunity to open things up as Finland has been determined as the weakest of the four teams especially on defence as they have been decimated with injuries.
If Canada can advance, they will be on a collision course with another match against the United States and it remains to be seen on how both teams will fare now that it will be switched to Boston.