The 19-year-old Boston Bruins sophomore forward has recovered from a fractured foot that had kept him out since 31 October. He recently completed a two-game conditioning stint with Boston’s AHL affiliate in Providence. Pastrnak, appearing in his third straight World Juniors, started on the top line with Michael Spacek and Jiri Smejkal.

About adjusting to his new surroundings in Helsinki, Pastrnak said: "It’s bigger ice at the World Juniors. It’s totally different hockey than I’ve been used to. I think as the tournament goes on, I’m going to feel better and better every day."

Dominik Lakatos had the other Czech goal.

Another star Czech attacker, Pavel Zacha, sat out with a lower-body injury. He aggravated it during the opening 2-1 shootout loss to Russia, but is expected to return to the lineup in the near future. Czech blueliner Alex Rasner did not play due to a knee issue, but should also be back soon.

It’s usually a tense battle when the two halves of the former Czechoslovakia clash, and this was no exception. For Czech goalie Vitek Vanecek and his Slovak counterpart Adam Huska, it was like a game of “chicken,” waiting to see who would blink first. Vanecek got his first career World Junior shutout as the Czechs outshot Slovakia 34-18.

"I feel good," said Vanecek. "I’m glad I have my first shutout of the tournament."

The Czechs, who suffered a 3-0 upset loss to Slovakia in last year’s quarter-finals, weren’t going to make the same mistake again. They turned the tables with a solid defensive effort. They’re seeking their first U20 medal since 2005’s bronze in Grand Forks, North Dakota.

The Slovaks shocked the hockey world by defeating Sweden in the 2015 bronze medal game. They now have a win and a loss after beating Belarus 4-2 to start this tournament.

In the scoreless first period, the Czechs dominated territorially and put the pressure on with Slovakia's Kristian Pospisil off for slashing. Shots favoured the Czechs 10-2. Slovakia didn’t get a shot on goal until well past the midpoint of the first period.

The Slovaks began shooting from every angle during a pair of second-period man advantages, but still couldn’t find the target.

"We played really good defensively," said Vanecek. "Our D-men blocked a lot of shots. It was a good effort."

The Hartwall Arena crowd amused itself by banging green noisemakers and rocking out to Ratt’s “Lay It Down” and Iron Maiden’s “Can I Play With Madness” between whistles as it awaited the first goal.

It finally came with 3:02 left in the middle frame. Pastrnak unleashed a wrister from the top of the left faceoff circle that beat Huska high to the glove side on the power play. The go-ahead goal came moments after Slovakia's Radovan Bondra was denied on a glorious shorthanded chance.

A flukey goal with 8:05 left in the third gave the Czechs some insurance. Lakatos had the puck go off his skate when he went hard to the net, and it then bounced in off Slovak defenceman Erik Cernak's skate. The goal was reviewed by the officials and deemed good.

Pastrnak said his team was motivated by memories of losing to Slovakia at the 2015 tournament: "Obviously we didn’t want to talk about it, but in the back of your mind, you still have it and you still remember it, especially the guys who were here last year."

The Czech-Slovak rivalry at the World Juniors, which dates back to 1997, has historically been lopsided in the Czechs’ favour. Overall, the Czechs have won 11 games, tied one, and lost four against their “little brothers.”

Next up on Wednesday, the Czechs take on Belarus and the Slovaks face host Finland.

"We’re pretty confident," said Vanecek. "We have to win."