The 18-year-old Laine, this year's Finnish playoff MVP with champion Tappara Tampere, is being touted as a potential rival to the U.S.'s Auston Matthews as the number one overall pick in the 2016 NHL Draft. Named Finland's Player of the Game, the imposing winger got the Day One edge, as Matthews was held pointless in a 5-1 loss to Canada.

"Laine is a different guy," said Finland's Leo Komarov. "He’s a little bit shy and doesn’t know us yet, but when you come up to the (senior) team in Finland, you can be yourself. We know who he is, he’s got a good shot, and he’s going to be a good player."

Mikael Granlund was likewise impressive with two goals and an assist, and Mikko Koivu and Antti Pihlstrom added singles for Finland. Aleksander Barkov picked up a pair of assists. Despite a slow start, it was a strong debut for coach Kari Jalonen's team.

"It was a great win by us," said Barkov. "We struggled for the first ten minutes but we started to believe in each other. We played a great game and scored a lot of goals."

Andrei Stas and Alexei Kalyuzhny replied for Belarus.

Finnish goalie Mikko Koskinen, the starter for the KHL's SKA St. Petersbug, looked quite at home, getting the win versus Belarus veteran Vitali Koval. Finland outshot Belarus 30-16.

It was a lively atmosphere at the packed Yubileiny Arena, with competing chants of “Belarus!” and “Suomi!” raining down.

Finland finished sixth at last year’s Worlds, while Belarus came seventh. The Finns medaled twice at the last five tournaments (gold in 2011, silver in 2014), while Belarus is still looking for its first medal of all time.

In the first period, Belarus had the better of the play, outshooting Finland 8-4. They gave no quarter, with pressure all over the ice, although they failed to cash in on two power play chances. Koskinen had to be sharp, foiling Geoff Platt’s in-tight backhand attempt, and blocking Sergei Kostitsyn’s quick release from the left faceoff circle.

Laine drew first blood on his first World Championship goal at 1:45 of the second period. He busted through the neutral zone, cut to the middle, slipped a tricky backhand pass to Barkov, and converted the return feed into a gaping net.

The Finns kept coming, as Belarus failed to maintain its high tempo of the first stanza. Koivu made it 2-0 at 12:28. The Finnish captain outmuscled defenceman Ilya Shinkevich as he bulled his way to the net along the goal line and shoved the puck in.

"The key to the match was the second period when we started to play as a team," said Jalonen.

At 17:55, Stas cut the deficit to 2-1 with a great shorthanded rush against the flow. Finnish defenceman Juuso Hietanen turned over the puck at the Belarus blue line, and Stas eluded the backchecking of Laine to tuck a backhander past Koskinen while falling.

But that incident just seemed to get the big blonde Finnish kid going.

Forty-one seconds later, Laine made amends on a 5-on-3 power play. Koivu set him up to hammer home a one-timer from the top of the left faceoff circle. And then, Laine got it across to Granlund for another man advantage marker, ending Belarus's hopes with a 4-1 lead with four seconds left in the middle frame.

"In the second period we came out flat and started taking penalties and that hurt us," said Belarus forward Charles Linglet. "They’ve got some pretty good players on the power play and our pk had a hard time keeping up."

In the third period, Pihlstrom put Finland up 5-1 at 2:01 with a high glove-side goal on the rush.

Koval had some rough luck on the 6-1 goal, as Anssi Salmela's center point drive rattled his mask and Granlund tucked in the rebound at 7:51.

Kalyuzhny, the Belarus captain, gave his fans something to cheer about when he rounded out the scoring at 6-2 at 11:01.

Belarus has only beaten Finland once in nine tries at the IIHF World Championship. It was a 2-1 shootout win on May 2, 2009. Oleg Antonenko scored the decisive goal.

Finnish goalie Niklas Backstrom did not dress for this game. The two-time Olympian has been designated as the third-stringer in St. Petersburg. Backstrom, 38, was Finland’s starter at the 2008 Worlds in Canada en route to bronze.

Next up, Belarus faces the Americans on Saturday. Finland will battle Germany on Sunday.

"We know the U.S. is going to be tough but maybe even tougher because it is back-to-back games," said Linglet. "But it will be a good one."