Move over duopoly because the time has come to furrow your brow about the “triopoly.” Many marketers and publishers have grown tired of the dominance of Google and Facebook in the digital advertising space. Now they can add Amazon to the list of dominant tech rivals. eMarketer now predicts that Amazon will hit $4.6 billion in U.S. ad revenues for a 4.15% share of the digital ad pie this year. And its growth rate of 400%+ per year will get it to a 15% share by 2020.

You’ve probably notices that Amazon has sponsored search ads all over its e-commerce pages, enticing consumers to buy relevant products. However, it’s offering much more than that, from video ads to traditional TV ads to ads on its cardboard delivery boxes. The only problem is that it competes with its own advertisers by selling Amazon brand products alongside merchant listings. And more recently it went too far by promoting sponsored items in baby registries.

In short, if Amazon is going to be the third wheel on the triopoly tricycle, it can expect withering scrutiny from the media, marketers and eventually regulators if it doesn’t play fair.

So many ways to dominate

How did Amazon sneak up on us to become such a dominant ad player? By boring us to death. Those little sponsored links on product pages? How quaint. A sponsored related product, or a banner ad on a Kindle? Yawn. This is the same way that Amazon itself has dominated the world thanks to… cloud servers for your website or business. The engine for Amazon’s profits has long been Amazon Web Services, not its e-commerce business.

This sleight of hand works just as well in the ad business. While you were considering how they would deliver your packages via drones, Amazon was bulking up on advertising through its self-service system, placing sponsored items all over its pages. And then finally, in the sleepy days after Thanksgiving, while the country still was drowsy from tryptophan, the Wall Street Journal trumpeted that Amazon had arrived, “with little fanfare” as a new advertising behemoth.

Helpfully, the WSJ pointed out all the ways that Amazon was going to dominate in advertising. According to a Cowen & Co. survey of ad buyers, 29% buy sponsored product ads, 21% buy video ads on IMDB and Amazon.com, and 13% buy good old display ads. But there’s been more, with “The Minions” movie buying ads on delivery boxes, and a yogurt company paying to include instructions in Amazon Pantry boxes on how kids could build rockets and airplanes out of those boxes. Cute.

And the content play too

While those sponsored links followed the time-honored tradition of Google becoming a dominant ad player with its own AdWords offering way back when, Amazon is ready to spread its wings too. The video ads referenced above could explode if and when Amazon launches a rumored free ad-supproted Free Dive video service for users of its Fire TV devices.

While there is no advertising on its Prime Video service, Amazon has become a major player in content by spending $5 billion this year, according to a JPMorgan analyst. That’s less than the $8 billion that Netflix shelled out, but more than typical TV broadcast networks. And Amazon does serve TV-style ads into its streams of NFL Thursday Night Football games – as well as Premier League soccer games.

And that might grow as well if Amazon is successful in its bid for the 22 regional sports networks that Disney is selling as part of its buyout of 21^st Century Fox properties. That type of marquee purchase (which includes the New York Yankees’ YES Network) might finally open the floodgates for tech giants to get into sports programming and break the final blockade for cord-cutters.

Missteps and conflicts

But what might stall Amazon in that pursuit is what might stall the company in its overall ad ambitions: creating too many conflicts of interest. Would Disney really want to sell the regional sports networks to Amazon, a company that is trying to eat its lunch in streaming content? And how many retailers will continue to feature their content on Amazon, and pay Amazon for sponsored slots, when they are being squeezed out by Amazon’s own retail brands?

You can hear the frustration in the story of Jason Boyce, CEO of Dazadi, a home recreation retailer that has to pay for placement on Amazon. “They get all the prime real estate [for their brands]. It’s unfair,” Boyce told the Journal, but “we have to be on Amazon.”

Even more unfair are the sponsored links Amazon runs in private baby registries, with a tiny gray “sponsored” tag. The sponsored items were not chosen by the parents-to-be and led some confused friends and family to buy those items, upsetting everyone involved. After a Wall Street Journal story about the practice, Amazon said it was phasing them out.

And that’s where the rubber meets the road for Amazon as it moves stronger into the digital ad business, with one of its HQ2 offices right outside Manhattan, the epicenter of advertising. If it wants the power of being a digital content and ad player, it will have to come clean on its ambitions and compete fairly or users will tune out. And let’s face it: If the U.S. Congress, FTC and other regulators won’t do their job to keep the tech giant in line, we can expect the EU to come down harder.