Dec 17 (Reuters) - North America"s major sports leagues were struggling to contain an explosion of COVID-19 outbreaks on Thursday as fans were bracing for a holiday season of disruption. For three days the National Football League, National Hockey League and National Basketball Association have faced a surge in positive tests, forcing players into league-mandated COVID-19 protocols and the postponement of games. The holiday season across the United States and Canada is usually filled with sport action with everything from college football Bowl games to the NBA"s Christmas Day showcase. There is no indication yet that any holiday action will be postponed but with the coronavirus spreading through locker rooms, fans may not see all their favourite players. The NHL"s Montreal Canadiens hosted the Philadelphia Flyers without fans on Thursday after receiving a request from Quebec public health officials due to the "spiraling rise of COVID-19 cases in the region". "We have obtained assurances that beginning with our games in January, we will return to a partial capacity scenario and be able to host fans once more," the Canadiens said in a statement, encouraging fans to get vaccinated and receive booster shots. The NFL, which had around 100 players test positive this week, updated its COVID-19 protocols on Thursday, requiring masks regardless of vaccination status, eliminating in-person meals and barring outside visitors while teams are traveling. The NFL told Reuters there are no plans to limit stadium capacity given that, with few exceptions, players do not interact with fans on game day. NBA PROTOCOLS In Canada, some people who get tickets to see the NHL"s Toronto Maple Leafs and Ottawa Senators or NBA"s Toronto Raptors as Christmas presents may be out of luck as the Ontario provincial government is implementing a 50% capacity limit for sporting events starting on Saturday. Already dealing with a backlog of 10 postponed games, the NHL on Thursday was looking at the possibility of more scheduling headaches. With COVID-19 running rampant through their locker room the Calgary Flames said on Thursday that two more players had entered protocol bringing the total to 18. With almost the entire team in quarantine, the NHL said it was delaying Calgary"s return to the ice until at least through Dec. 18. The International Ice Hockey Federation, which organises the world junior hockey championship that will be held Dec. 26-Jan. 5 in Alberta, did not immediately respond when asked by Reuters in an email if there was talk about limiting attendance. The premier of the western Canadian province, however, said this week there were no plans to change capacity levels in the two arenas that will host the 31-game, 10-team tournament. The NBA on Monday saw its first games of the season postponed when 10 Chicago Bulls players and additional staff members were placed in health and safety protocols requiring the rescheduling of two contests. The league and its players" body agreed to new COVID-19 protocols for the holiday season, including increased testing, in a memo sent out to teams, ESPN reported. A return to using masks in most circumstances was also outlined in the memo, including during travel and while on the bench in games. The virus has also impacted college sports, including at Tulane University in New Orleans where the men"s basketball team has been temporarily shut down due to multiple positive cases of COVID-19 within the program. The decision resulted in the cancellation of two games.