BUFFALO, N.Y. -- Samuel Bucek scored an unassisted goal with 2:08 remaining in the third period to give Slovakia a 3-2 victory over the United States at the world junior hockey championships on Thursday.
Filip Krivosik scored the other two goals for Slovakia, and Roman Durny made 43 saves in his world junior debut.
Casey Mittelstadt and Brady Tkachuk had goals for the U.S., which had won nine straight world junior games entering the night. The U.S. began its streak with the 2016 bronze medal game and went undefeated in winning the gold medal last year in Toronto. The previous American record was eight consecutive victories from 2004 to 2005.
The U.S. faces Canada in an outdoor game at the Buffalo Bills' New Era Field on Friday afternoon.
In other preliminary-round games, Sweden beat the Czech Republic 3-1, Russia pulled away in the third period for a 5-2 victory over Switzerland, and Finland defeated Denmark 4-1.
Slovakia is 4-13-1 all time against the U.S. in the world junior championships and had lost six straight preliminary-round meetings since last defeating the U.S. in a 2009 quarterfinal.
Bucek made an outstanding individual effort to score the winning goal, maneuvering around three defenders and circling behind the net before slipping the wraparound past Joseph Woll, who stopped 22 shots for the U.S.
Mittelstadt tied the game for the U.S. with 3:11 left in the third period.
Following a 9-0 rout of Denmark on Tuesday, the U.S. got off to a sluggish start in a game it never led.
Krivosik gave Slovakia a 1-0 lead five minutes into the second period. He put Slovakia ahead 2-1 on a backhand with 4:45 left in the third period.
Ryan Poehling set up Tkachuk for the tying goal on a 2-on-1 midway through the second period.
Earlier, Alex Nylander had a goal and an assist, and defenseman Rasmus Dahlin, the expected top pick in next year's NHL draft, had two assists to lead Sweden.
Marcus Davidsson and Elias Pettersson also scored goals as Sweden improved to 2-0 in preliminary play. Filip Gustavsson made 24 saves.
Filip Zadina scored the Czech Republic goal to make it 2-1 late in the second period. Jakub Skarek stopped 34 shots.
Artur Kayumov and Georgi Ivanov scored third-period goals to lead Russia over Switzerland. Kim Kostin and Vladislav Syomin each had a goal and an assist, Andrei Svechnikov had two assists, and Vitaly Abramov scored an empty-netter for the Russians, who are 1-1 in preliminary play.
Marco Miranda and Ken Jager scored for Switzerland. Philip Wuthrich made 32 saves. Jager's goal tied the game at 2-2 early in the third period before Kaymov scored the go-ahead goal with 8:58 remaining.
Juuso Valimaki and Henri Jokiharju both had a goal and assist for Finland in its win over Denmark.
Joona Koppanen and Aapeli Rasanen scored the other goals to give Finland a 2-0 lead in the first seven minutes. Miro Heiskanen had two assists, and Ukko-Pekka Luukkonen needed to make just six saves. Finland improved to 1-1 in group play.
Kasper Krog stopped 58 shots for Denmark. Nikolaj Krag scored Denmark's first goal of the tournament following a 9-0 loss to the United States in the opener.
Krag scored on a power play to make it 2-1 early in the second period. Finland pulled away when Valimaki and Jokihariu scored two minutes apart late in the period.