The triumph enables Russia to advance to the semifinals on Saturday against the winner of the quarterfinal later Thursday between Sweden and Slovakia (1:30 p.m. ET, NHLN-US). The Russians lost 3-2 to Sweden in the final game of the preliminary round in the Group B pool Tuesday.
"We want to play Sweden," Zadorov told the IIHF website. "It was a close game last time and we're going to watch some video and play better."
After earning medals in two of the past three World Junior tournaments, including the gold at the 2013 WJC in Ufa, Russia, the Americans will go home this year without a medal.
Stefan Matteau had a goal and an assist, and Ryan Hartman and Nicolas Kerdiles also scored for the U.S. Goalie Jon Gillies made 20 saves.
"It's definitely disappointing," Hartman told NHL.com. "We came in with a goal to win gold and obviously fell short. It's a learning experience for the guys coming back next year; it's a good learning tool for them. Hopefully they'll be able to do a better job than we did this year."
Playing a huge part in the triumph for Russia was goalie Andrey Vasilevskiy who finished with 30 saves, including 16 during the final two periods. Vasilevskiy, a 2012 first-round pick (No. 19) of the Tampa Bay Lightning, rebounded well after allowing three goals on 17 shots in the opening 20 minutes.
His best save in the third came at 11:09 when he denied Hartman, a 2013 first-round draft choice (No. 30) of the Chicago Blackhawks, off a strong move to the slot on a play that resulted in a Russian penalty. He also stopped American defenseman Matthew Grzelcyk with less than one minute remaining on a blast from the left faceoff dot and Gillies pulled for an extra attacker.
New York Rangers prospect Pavel Buchnevich scored two goals for Russia, including an empty-net goal with 28 seconds left, and Edmonton Oilers prospect Anton Slepyshev had three assists. Slepyshev, the Russian captain, was named his team's best player of the game.
Zadorov, chosen by the Buffalo Sabres with the 16th pick of the 2013 draft, scored a pair of power-play goals in a span of 1:01 in the second to give his country a 4-3 lead. Both goals were scored with Russia on a 5-on-3 advantage after the Americans were assessed three minor penalties in a 57-second span.
"The power plays were the game changer," Russian forward Mikhail Grigorenko said. "We scored two goals. We took the lead and we kept it. Those two 5-on-3s in a row were the key."
U.S. coach Don Lucia agreed.
"Other than two five-minute segments of penalties [against Canada on Tuesday and Russia on Thursday], I thought we played well," Lucia said. "The players with 1995 birth years must learn that discipline is key, and going into next year's tournament realize how critical it is to have that discipline for certain minutes. [The officials] called the little trips and those penalties that maybe aren't going to be called in North America but that's on us. You have to adapt to that."
The first extra-man goal by Zadorov came with Matteau (tripping) and Thomas Di Pauli (hooking) in the penalty box midway through the period. Zadorov teed up a feed from Slepyshev in the right circle and blasted a shot past Gillies to pull his team into a 3-3 tie at 13:15.
Zadorov's second came with Di Pauli still in the box and Steven Santini (delay of game) off the ice. That's when Zadorov took a pass from Slepyshev and unleashed another bomb from the center of the blue line that beat Gillies over his glove to give Russia a 4-3 lead at 14:16.
Vasilevskiy was tremendous in the second with a few big stops to keep his team within 3-2. After a shaky first period, the 6-foot-3, 200-pounder turned away all seven shots he faced in the middle period. His finest came six minutes into the period when he denied Hartman off an odd-man rush with Grzelcyk when he threw out his right pad at the last second. He later stopped Di Pauli while hugging the right post at 7:43.
"I think he made a heck of a save there," Hartman said. "I just needed to elevate that a little more but those types of saves happen. It was a turning point in the game."
Lucia, whose team finished 0-for-5 on the power-play, called it the save of the game.
"I think he made a couple of critical saves when it was 3-2," Lucia said. "That one against Hartman was big. I thought once we adjusted to how good they were down low and how quick and strong they were in our own zone, we started clicking. I give the boys credit for taking a 3-2 lead, and then for the first segment of the second period I thought we were playing exactly the way we wanted to play … until the penalties."
In a bit of a shakeup, Lucia opted to make a shift on left wing on his second and third lines. He promoted Matteau to the second unit alongside Hartman and center Jack Eichel. Adam Erne, who had played the entirety of the tournament in that spot, was shifted to Matteau's spot on a line with Hudson Fasching and center Andrew Copp.
The move seemed to reinvigorate Matteau, who had a goal and an assist in the opening 20 minutes when the teams combined for five goals.
The U.S. took its first lead late in the first when Kerdiles collected a waist-high pass from Riley Barber at the Russian blue line and whipped a shot past a surprised Vasilevskiy high to the short side at 16:51 for a 3-2 edge. The goal came minutes after the U.S. had pulled into a 2-2 tie when Hartman took a pass from Matteau while skating hard down the slot and beat Vasilevskiy with a backhand shot at 11:23.
"I thought our discipline and our penalty kill were the reasons we were eliminated," Hartman said. "Last year we allowed just three goals [in 28 times shorthanded] for the whole tournament. I think we allowed three power-play goals in the first three or four games this year. That was another thing we stressed from the beginning."
The Americans, who went 4-for-6 on the penalty kill against Russia, allowed six power-play goals in 21 times shorthanded at the tournament.
Grigorenko, a first-round pick (No. 12) of the Buffalo Sabres in 2012, gave Russia a 1-0 lead 6:17 into the first when he took a feed from Slepyshev and scored his team-leading fourth goal. The U.S. squared the contest when Matteau cleaned up a rebound at 8:50. Eichel made the play happen when he skated hard down right wing, curled behind the Russian net and got a shot on Vasilevskiy that the Russian goalie stopped, but Matteau scored on the rebound.
Russia took a 2-1 lead when Buchnevich jammed a shot home off the right post while Gillies was sprawled on the ice at 9:11.
Panthers prospect Ian McCoshen finished the tournament with four penalty minutes, -1 and two shots in five games for the United States.