Team Canada forward Tyler Seguin suffered a lower-body injury and will not compete in the World Cup of Hockey, Hockey Canada announced Tuesday.
The exact type or extent of the injury is not known.
Buffalo Sabres center Ryan O'Reilly will replace the injured Seguin on the roster. Seguin played 13-plus minutes and had five shots on net in a preseason game against Team USA on Sept. 9.
"It's never easy to lose a player to injury, let alone one of Tyler's caliber, but once again, it speaks to the depth of talent in the country to be able to add a Ryan O'Reilly to our team," Team Canada general manager Doug Armstrong said. "Ryan just won gold at worlds alongside a number of our players in that dressing room, so we're expecting him to be able to jell quickly as we wrap up our pretournament against Russia. On behalf of our coaching and management staff, and all of the players, we want to welcome Ryan and wish Tyler a speedy recovery."
Seguin, 24, won a gold medal with Team Canada at the 2015 world championship. This was supposed to be his second international competition for Team Canada.
"I'm disappointed that I can't represent Team Canada at the World Cup of Hockey," Seguin said in a statement put out by the Dallas Stars, his NHL team. "Any time your country calls, it's a great honor and is something every kid from Canada dreams about getting the chance to do. While I'm upset that I don't get the opportunity to play, I understand the situation Team Canada is in with a short tournament.
"I wish all the best for that team, and the good news is that I'll get to be with my Stars teammates from day one. We're excited to get the season going, and we can't wait to get to Cedar Park [for training camp in the Texas city] and get to work."
Stars general manager Jim Nill said Seguin will return to Dallas "in the coming days" and the team will evaluate him when he arrives.
A source told ESPN's Craig Custance that early indications are that Seguin shouldn't miss much of the Stars' training camp with the injury.
Seguin finished second in scoring for the Stars during the 2015-16 season, posting 33 goals and 30 assists for 73 points. He missed the final 10 games of the regular season with an Achilles tendon laceration. He played one game in the Stanley Cup playoffs.
Canada plays its first World Cup game on Saturday against the Czech Republic.
The Associated Press contributed to this report.