Brady Tkachuk of the United States screens Roman Durny of Slovakia in the first period Thursday night. Getty Images

Team USA's road to a World Junior Championship repeat hit a speed bump on Thursday night in Buffalo.

Following a dominant 9-0 opening win against Denmark on Tuesday, the United States returned to action with a more challenging matchup against Slovakia on Thursday.

The scoring didn't get underway until the second period and it was the Slovaks who drew first blood. About five minutes into the middle frame, forward Filip Krivosik led a Slovakia two-on-one into the Americans' zone and fired a wrister five-hole on USA goalie Joseph Woll to take the 1-0 lead.

Team USA's response came about six minutes later when Brady Tkachuk turned the jets on in transition and received a great pass from Ryan Poehling. Tkachuk showed off his control at speed and used a nifty move to the backhand to answer with a five-hole tally of his own. 

Both teams carried the 1-1 tie late into the third period, but Slovakia reclaimed their lead with 4:45 remaining thanks to Krivosik's second goal of the night. The 18-year-old shelved an impressive backhander past Woll, striking a little bit of fear into the hearts of American fans.

That fear was quelled a minute and a half later when USA star Casey Mittelstadt brought an incredible effort for the equalizer. Mittelstadt stripped a Slovakia player of the puck in the neutral zone and charged towards the Slovakia net, burning a defender and the goalie with back-to-back nifty moves before tucking the puck into the back of the net to tie the game 2-2.

But Slovakia would not be kept down, and they responded by delivering the game-winning blow less than a minute later. It came via a strong effort from Samuel Bucek, one that was aided by some absolutely disastrous defense from the American boys. 

That was all she wrote, as the final horn sounded and Slovakia came away with a huge upset win to snap the Americans' nine-game winning streak at the World Juniors.

It was an ugly and disappointing showing for the United States, but it's still early in the tournament and they have a chance to bounce back, learn from their mistakes and tighten up play moving forward. They'll have a great chance at immediate redemption when they head outdoors to face Canada on Friday afternoon in Buffalo. If Canada wins, they'll all but lock up the top spot in Group A heading into the medal round.

Which NHL prospects came up big?

After dropping their opener earlier in the week, Finland came up with a 4-1 win over Denmark in which they dominated play for most of the game, outshooting the Danes 62-7. The impressive Finnish blue line had a great showing in the win -- including Henri Jokiharju and Juuso Valimaki, who both had a goal and assist each. 

Jokiharju, who was selected 29th overall in 2017 by the Chicago Blackhawks, continued to show off his ability to generate offense when he tallied his second goal of the tournament with a shot in traffic at the top of the crease. 

Valimaki, who went to the Calgary Flames with the 16th overall pick in 2017, had a beauty of a one-timer from the blue line to find the back of the net.

A handful of Russian players came away from their win against Switzerland with a couple of points, including Klim Kostin (St. Louis Blues prospect), Andrei Svechnikov (projected top pick in 2018), and Vitali Abramov (Columbus Blue Jackets prospect).

Defenseman Timothy Liljegren was a force in Sweden's matchup against the Czech Republic, picking up an assist in a 3-1 win. However, the box score didn't give him credit for his best play of the day, so we'll do it right here. The Toronto Maple Leafs prospect fired a beautiful outlet pass from behind his own net that led to Sweden's first goal of the day. 

The sequence was a very pretty one (especially the setup by Capitals prospect Axel Jonsson Fjallby) but Liljegren missed out on an assist because two guys touched the puck before it was buried. Regardless, this kind of breakout skill is a big reason why the 18-year-old went in the first round last summer.

Swedish forward Elias Pettersson, who went fifth overall to the Canucks in the 2017 draft, has an excellent shot and he's not afraid to use it. The 19-year-old led all players with a whopping nine shots during Thursday's win, and he converted on one of them with a power-play goal in the first period. The 19-year-old went bar-down for his second goal in as many games.

The Czechs only scored once on Thursday but it was a pretty goal nonetheless. Carolina Hurricanes propsect Martin Necas (12th overall pick in 2017) used some sauce to Filip Zadina, who is projected to be a top pick in 2018. The 18-year-old Zadina showed off his great finishing ability with a one-timer that snuck off the post and in for a power play tally. 

Buffalo Sabres 2016 first-round pick Alex Nylander (son of former NHLer Michael Nylander and younger brother of Leafs winger William Nylander) picked up his first tally of the tournament with a power play goal of his own. The skilled winger has a great release with excellent finishing ability, so if he can develop his all-around game and find more consistency, we could be seeing a lot more of this at the NHL level.

Arguably the best American player on Thursday night was 18-year-old Brady Tkachuk, who is the son of former NHLer Keith Tkachuk and younger brother of Calgary Flames star Matthew Tkachuk. Brady is expected to be a top pick in 2018 thanks to his combination of skill, speed, size and toughness, and he put on a great showcase of those abilities against Slovakia. 

Tkachuk's big highlight came in the second period when he was able to capitalize on a USA rush with a move to the backhand and a five-hole finish. Credit also goes to St. Cloud State star and Montreal Canadiens prospect Ryan Poehling for setting up the goal with a great centering pass that found Tkachuk in stride.

Sabres prospect Casey Mittelstadt once again put on a show for his soon-to-be hometown fans in Buffalo with an amazing effort late in the third period for an equalizer against Slovakia. They often say big-time player make big-time plays at big-time moments, and Mittelstadt went into full hero mode with this great highlight. 

What else happened in the preliminary round?

It was a busy day in Buffalo, with three other game on the schedule besides USA's game versus Slovakia.

  • Finland outshout Denmark 62-7 en route to a 4-1 win
  • Russia scored three late goals to escape a scare from Switzerland, 5-2
  • Sweden picked up their second straight victory with a 3-1 win over Czech Republic

What happens next in the World Juniors?

Friday will be a light day with only two games on the schedule, but it will also feature the marquee matchup of the preliminary round. Team USA will meet Canada outdoors at New Era Field for a rematch of last year's gold-medal game. The contest will kick off at 3 p.m. (weather permitting) and will be broadcast on TSN and NHL Network.

The 2018 World Juniors preliminary round continues through Dec. 31 before relegation in January, which precedes the playoffs. Here's a complete rundown of the next wave of games through the end of the year:

Friday, Dec. 29

  • Russia vs. Belarus, 12 p.m. (NHL Network, TSN3)
  • United States vs. Canada, 3 p.m. (NHL Network, TSN)

Saturday, Dec. 30

  • Belarus vs. Czech Republic, 12 p.m. (NHL Network, TSN 1/4)
  • Switzerland vs. Sweden, 2 p.m. (TSN5)
  • Slovakia vs. Finland, 4 p.m. (NHL Network, TSN 1/4/5)
  • Canada vs. Denmark, 8 p.m. (NHL Network, TSN 1/4/5)

Sunday, Dec. 31

  • Czech Republic vs. Switzerland, 12 p.m. (NHL Network, TSN 1/3)
  • Finland vs. United States, 4 p.m. (NHL Network, TSN 1/3)
  • Denmark vs. Slovakia, 6 p.m. (TSN2)
  • Sweden vs. Russia, 8 p.m. (NHL Network, TSN 1/3)