Mittelstadt was selected by Buffalo with the No. 8 pick in the 2017 draft.
BUFFALO, N.Y. (AP) The Sabres' top prospect, center Casey Mittelstadt, is leaving Minnesota following his freshman season after agreeing to a three-year, entry-level contract with Buffalo on Monday.
Mittelstadt is scheduled to join the Sabres on Tuesday, and could make his NHL debut as early as Thursday, when Buffalo hosts the Detroit Red Wings.
The agreement was reached a little over a week after Minnesota's season ended by failing to qualify for the NCAA Tournament. The Golden Gophers are also undergoing a change after coach Don Lucia announced he is stepping down following 19 seasons.
The 19-year-old Mittelstadt was selected by the Sabres with the No. 8 pick in the 2017 draft.
Mittelstadt had 11 goals and 19 assists in 34 games and was named to the Big Ten all-freshmen team this year.
He has already made a splash in Buffalo after creating several highlight-reel plays in representing the bronze-medal-winning United States team at the World Junior hockey championship, which was held in the city three months ago.
From Eden Prairie, Minnesota, Mittelstadt was named the 10-nation tournament's MVP after finishing tied for first in scoring with 11 points (four goals, seven assists).
Sabres general manager Jason Botterill was impressed by how Mittelstadt excelled at the world championships.
''With it being here in Buffalo, there was that added pressure,'' Botterill told The Associated Press in January. ''And I think you saw a player who instead of succumbing to the pressure, actually thriving in that type of environment.''
Mittelstadt's most memorable goal came in a in a 3-2 preliminary-round loss to Slovakia.
With the U.S. trailing 2-1, Mittelstadt stripped the puck from Marian Studenic at the Slovakia blue line and circled back into the zone. Mittelstadt kicked the puck between his legs to avoid a check by defender Michal Ivan and didn't break stride in cutting across the top of the crease and avoiding goalie Roman Durny. He swept a shot into the open left side with 3:11 remaining.
Mittelstadt joins a Sabres team that has already extended its franchise-worst playoff drought to seven years, and in jeopardy of finishing last in the overall standings for the third time in five seasons.
Buffalo has six games left after playing at Toronto on Monday night.
Mittelstadt will use up the first year of his contract this season. However, he would not be eligible to be exposed for selection in an expansion draft in 2020, should the NHL approve Seattle's bid to join the league for the 2020-21 season.
Mittelstadt's addition comes a day after defenseman Will Borgen elected to skip his senior season at St. Cloud State to sign a three-year contract with the Sabres.