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Nathan Horton will miss the rest of the Stanley Cup finals with a severe concussion, and Canucks defenseman Aaron Rome also is finished after the NHL suspended him for four games Tuesday for his late hit on the Bruins forward during Game 3.

Horton had just passed the puck early in the first period Monday night when Rome turned his shoulder and left his skates to flatten him. The 26-year-old Horton, the right wing on Boston's top line, apparently was knocked unconscious, hitting his head on the ice and staying down for several minutes before medical personnel took him away on a stretcher.

The Bruins saw it as a blindside hit — the type of blow that the league has tried to eliminate in the past year with Rule 48 after several players sustained severe concussions in recent seasons.

The Canucks vehemently disagreed Tuesday, uniformly claiming it was a legal blow to Horton's chest, only perhaps an instant late.

Mike Murphy, the NHL's senior vice president of hockey operations, agreed the hit would have been legal if it hadn't been late. But given its timing and Horton's subsequent injury, the NHL determined Rome would miss the rest of the series.

"I thought it was a late hit," Murphy said. "I thought that the body was contacted, but I also thought that the head was hit. It caused a serious injury to Nathan Horton. ... This has nothing to do with Rule 48. This is just an interference penalty, an interference hit. If it was immediate after he released the puck, it would be a legal hit. We have them all the time."

The Canucks vocally rushed to Rome's defense after practice Tuesday at Boston University, criticizing the severity of the suspension during the final postseason round. Game 4 is Wednesday night.

"We disagree with the decision, and it was a clean hit," Vancouver captain Henrik Sedin said. "Talking to Aaron was extremely emotional. When you get to this point in the playoffs, you want to be a part of it on the ice, and Romer didn't deserve what he got."

Rome didn't attend the Canucks' practice, but issued a brief statement through the team expressing concern for Horton's health and recovery.

"I try to play this game honestly and with integrity," said Rome, himself the victim of a serious hit from behind by San Jose's Jamie McGinn during the Western Conference finals. "As someone who has experienced this type of injury, I am well aware of its serious nature and have no desire for another player to experience it."

While Horton was taken to Massachusetts General Hospital, Boston rallied for an 8-1 victory, cutting Vancouver's series lead to 2-1. Coach Claude Julien said Horton stayed overnight for observation and left Tuesday morning.

"Obviously glad to know that it's not as bad as you always suspect," Julien said. "For him to be out ... obviously (there's) a long road to recovery, but hopefully he gets better soon."

Boston forward Milan Lucic, Horton's fellow wing on the Bruins' top line, said he had communicated with Horton by text message.

"He's feeling good, feeling a lot better," said Lucic, who turned 23 on Tuesday. "He sent me a birthday wish, so it's good he remembered my birthday after a concussion."

If the Stanley Cup is awarded before Game 7, the NHL said Rome's suspension will carry over to the start of next season.

While Horton is a key offensive player for the Bruins, the 27-year-old Rome is a depth defenseman for the Canucks, usually playing in their third pairing. He has one goal and 37 penalty minutes in the postseason.

"Obviously, it's not even-up when you look at those players' impact on the game, but it's our job to deal with it," Boston defenseman Andrew Ference said. "It's not the same, but that's the way those things usually work."

Horton has eight goals and nine assists in the playoffs for Boston. He's second in the NHL postseason with a plus-11 rating, and he already became the first player in NHL history to score a game-winning goal in a Game 7 twice in the same postseason run.

He skates alongside center David Krejci and Lucic on the Bruins' top line. Julien said rookie Tyler Seguin, a healthy scratch Monday night, is a candidate to replace Horton in Game 4.

Horton has been a hero in the postseason for Boston, which is in the Stanley Cup finals for the first time in 21 years. Horton scored the winning goal in overtime in Game 7 of the first round against Montreal — and again in the Eastern Conference finals, getting the only goal in Boston's 1-0 victory over Tampa Bay late in the third period.

Horton is in his first career postseason after spending his first six seasons with the woeful Florida Panthers. The former No. 3 overall draft pick has 168 goals and 180 assists in 502 games.

Horton was Boston's second-leading goal-scorer this season with 26, finishing fourth on the team with 53 points.

Vancouver already lost defenseman Dan Hamhuis to an undisclosed injury in Game 1 of the finals, but the Canucks are deep on defense, with veteran Keith Ballard sitting out the first three games as a healthy scratch.

"It seems like four games is pretty excessive in the Stanley Cup finals," Ballard said. "We're losing a guy who has played in a lot of situations for us, so it's tough."