FOXBOROUGH, Mass. -- The Toronto Maple Leafs are the front-runner to host the 2017 Winter Classic for their centennial season, although sources say it’s not a done deal.

There is concern in some league circles that Toronto’s sports market could be saturated in late 2016, with the World Cup of Hockey in September, the CFL Grey Cup in November and part of the world junior championship in late December/early January, all being held in Toronto.

So the internal debate at the league’s head office right now is whether Toronto should instead get a Stadium Series outdoor game later in the season to distance it from those events.

The Maple Leafs, like the NHL, are celebrating their 100-year anniversary next season, so either way, sources say an outdoor game at BMO Field is likely. The question is whether it’s the Winter Classic on Jan. 1 or a Stadium Series game later in the season.

The New York Rangers are the front-runner to play the Leafs in the Winter Classic should Toronto get it, although there are a few other teams in the mix, sources said.

Should Toronto not get the Winter Classic, sources said a Philadelphia Flyers-Pittsburgh Penguins matchup is possible for Jan. 1, either at Lincoln Financial Field in Philadelphia or Heinz Field in Pittsburgh.

Much of this is in flux, but there’s a time pressure on the league to make a decision soon, according to sources.