LAKE PLACID, N.Y. -- A year ago, William Karlsson made Sweden's team for the 2012 IIHF World Junior Championship as a fourth-line player who wasn't expected to see a lot of ice time.
He had had a goal and an assist in six games, and by the time Sweden had won the gold medal, he was playing on the second line and was a key contributor to the team's championship.
Karlsson, a 2011 second-round pick of the Anaheim Ducks, kept that strong play going through the second half of his season in Sweden, and it carried into Sweden's game against Finland on Tuesday at Herb Brooks Arena -- he had a hat trick in an 8-2 win.
Teammate Viktor Arvidsson scored a pair of goals, and Filip Forsberg had a goal and two assists. Pontus Aberg and Max Gortz also had a goal each, and goalie Oscar Dansk stopped 23 of 25 shots.
Robert Leino and Juuso Ikonen scored for Finland. Goalie Janne Juvonen allowed eight goals on 39 shots.
A number of those came from Karlsson, whose snap shot from the dot in the left faceoff circle at 5:44 of the second period gave Sweden a 3-2 lead. He added a pair of goals in the third period to pad Sweden's comfortable lead.
"He has matured a lot as a guy and I think it reflects on the ice," Sweden coach Roger Ronnberg told NHL.com. "He's more of a man now. He was a young boy a year ago and now he looks more like a man."
Karlsson, 19, said he feels like he's gotten stronger physically and emotionally, and it's starting to show on the ice. He centered the team's top line Tuesday, flanked by Nashville Predators prospect Pontus Aberg and Forsberg, the Washington Capitals' top pick in June.
"I think I've grown a lot since last year when I made the [World Junior] team," Karlsson told NHL.com. "That confidence, I've just kept it going. Now I am hopefully a big part of this team to play in the  World Juniors."
After Karlsson's strong outing for Sweden in Alberta, he finished a season with Vasteras in Sweden's Allsvenskan with 45 points in 46 games, which helped him earn a contract with Swedish Elite League club HV 71.
It's exactly what the Ducks have been hoping to see since selecting the center with the 53rd pick in 2011.
"I think over the last two years the one thing that William needed to work on is strength and muscular mass," Ducks director of amateur scouting Martin Madden told NHL.com. "His No. 1 asset is his hockey sense. He's put on some good weight, he's much stronger on the puck, and I think it showed today."
Madden said he expects Karlsson to spend at least one more season in Sweden, continue to develop, and potentially compete for a spot with the Ducks in 2013-14.
"I think the natural progression is for him to step up to the elite-league level in Sweden as a 19-year-old and play lots of important minutes there," Madden said. "I think he's able to do that. I think he's slotted in a second-line role to start the season there. And I think that's the best path for his development."
The teams were tied 1-1 after one period Tuesday, but Finland came out harder to start the second, taking the lead 55 seconds in to the period when Chicago Blackhawks first-round pick Teuvo Teravainen made a sensational juggling play to hold the puck in the offensive zone, then made a sharp pass to a cutting Ikonen for the forward's third goal in two games at the Junior Evaluation Camp.
The tide turned minutes later as Sweden scored twice in a 59-second span. Arvidsson took a pass from Emil Lundberg and drove to the net, and as he fell through the crease, he pushed the puck under Juvonen at 4:45 to tie game. Less than a minute later, Karlsson's rocket from the dot flashed past Juvonen's glove to make it 3-2 for Sweden.
Gortz and Aberg beat Juvonen up high to extend the lead to 5-2 after 40 minutes. In the third, Karlsson scored twice, sandwiched around a goal by Forsberg.
Despite the result, Ronnberg wasn't putting a lot of stock in it.
"I think we showed some skill up front at forward," he said. "We had some good goals there, we were really effective today, but it wasn't our best game."
Sweden is off until Thursday, when it plays the United States. Finland returns to the ice Wednesday for the first of its two games against Team USA.
Contact Adam Kimelman at email@example.com. Follow him on Twitter: @NHLAdamK