Unlike the broadcast networks that have traditionally served as the NFL’s primary TV partners, Netflix has always generated most of its revenue from subscriber fees, not ad sales. But as Netflix prepares to show two NFL games on Christmas Day, it’s selling commercials. And business is booming.

Netflix has already sold out of all its commercial inventory for the Chiefs-Steelers and Ravens-Texans game on Christmas, according to the Hollywood Reporter. That includes big deals with FanDuel to be the official sports book partner and Verizon as the kickoff sponsor.

The NFL is the biggest draw on American television, and there isn’t a close second. Which means it’s the programming that advertisers most want to be associated with, and will pay the most to appear on. It’s unsurprising that Netflix hasn’t had any trouble selling ads for the seven hours or so of live NFL programming it will show to America on Christmas Day.

Netflix has also partnered with Nielsen to measure its audience for the two Christmas games, which will provide a more valid comparison for the Netflix games with traditional network and cable programming. (The numbers often cited for Netflix viewership of hit shows like Squid Game or Stranger Things are typically not apples-to-apples comparisons with the viewership of cable and network shows.)

Advertising is still not a major source of revenue for Netflix, but as it begins to become a major player in live sports (starting with Friday’s Jake Paul-Mike Tyson fight at the Cowboys’ AT&T Stadium in Dallas) it will also become a bigger player in selling commercials, and it won’t be surprising if that means the NFL’s relationship with Netflix continues beyond this Christmas.