The Super Bowl is Twitter's biggest annual event, and sources say it's also the biggest revenue day, as brands look to boost their TV ad spend and tap into a huge audience multitasking during the game.
With as many as 85 percent of ads expected to feature hashtags this year, it should be the biggest year for social Super Bowl conversation ever.
The question is how Twitter will tap into Sunday's conversation to hook consumers and grow its user base. And we'll see whether a new play from Facebook in Twitter's Super Bowl ad territory will help the social giant attract more of the public conversation around the big game from Twitter.
This year Twitter is trying to make it easier for users to find relevant content, inviting viewers to click over from their timeline to its new NFL Experience. The page gathers all sorts of relevant NFL-related content—stats, photos, videos and tweets—to encourage users to share more and stay engaged.
It's part of a larger push that Twitter is making to build on the huge Super Bowl-related conversation each year and accompanying ad dollars. During last year's telecast there were about 25 million tweets sent about the game and halftime show, and that doesn't include retweets, favorites, replies or other interactions.
The company is working with advertisers to make them savvier players in the conversation by embedding employees in brands' social media "war rooms."
This year the company will have a presence in as many as 15 brands' war rooms around the country, including Budweiser, Bud Light, American Family Insurance and Coca Cola, up from just five war rooms last year.
The idea is for Twitter to help brands plan ahead about how to weigh in on the game, and even more important, how to react in real time, as Oreo famously did with its "You can still dunk in the dark" tweet that went viral.
And on the day after the game Twitter will release what it is calling Top Spot analysis of the most popular Super Bowl ads. It'll look at the timing and context within tweets, to figure out which ads people liked the most, even if tweeters don't use hashtags.
But this year Twitter is facing more competition as the second-screen companion to the game, from Facebook. The social giant just this Wednesday announced a new Super Bowl Experience page.
It is similar to Twitter's NFL timeline experience in that it aims to give fans one place to find posts from friends and people around the world, as well as scores, photos and videos from news outlets, the NFL, teams and players.
The key thing about this new play from Facebook is that it's part of a larger play to be more than just conversation and sharing among friends. And in December, Facebook struck a deal with the NFL to post short NFL clips on the social network, followed by ads from Verizon Wireless, which is paying to promote them in NFL fans' news feeds.
Becoming a bigger part of the conversation about the Super Bowl also plays into Facebook's push to build its video platform, which means competition with Twitter's new video player, and play for video ads. But even more so, Facebook's video ads are an attack on YouTube.
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YouTube always gets a huge boost around the Super Bowl. Last year people watched more than 6.3 million hours of ads on the video-sharing site. This year Facebook is pitching advertisers to post their spots directly into Facebook, in its native video player.
Advertisers from GoDaddy to a newcomer to the game, Wix, are making the leap because videos show up more frequently in users' feeds than other posts, and by one measure Facebook video ads get six times the engagement of a YouTube link.
Raising its profile with game-related content gives Facebook an opportunity to target YouTube's reputation as the destination for digital video, looking for a piece of YouTube's projected $3.5 billion in revenue this year, as well as TV ad dollars.
YouTube is fighting back by upping its Super Bowl game, streaming its own halftime show on its AdBlitz channel featuring 20 YouTube creators and musicians, enabling brands to connect with viewers who prefer ads to the game.
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Correction: An earlier version of this story misstated the number the number of brand war rooms Twitter would attend.
Disclosure: CNBC's sister company NBC Sports broadcasts the Super Bowl.