As digital ad spend around the globe is set to balloon, nearly doubling over the next four years, could the digital duopoly face a disruptor?

U.K. research firm Juniper Research’s new analysis shows that Amazon, which has been long-watched as a rising digital powerhouse but still generally regarded as a tier down from the behemoths (a.k.a. Facebook and Google), could see growth of 470% by 2023, reaching $40 billion (all figures in U.S. dollars) in ad revenue – putting Amazon at a 7.7% share of the total global digital ad spend ($520 billion in 2023).

That’s up from just a 3% share in 2018.

Juniper’s assessment of Amazon states that the company’s heavy investments in machine learning will offer very efficient targeting across its growing advertising platforms, possibly even attracting users away from the established Google/Facebook duopoly.

Google, for its part, will continue to grow, with ad revenues expected to exceed $230 billion in 2023 – still taking a major chunk of the digital ad market, a 44.2% share. While it might seem like the gap between Amazon and Google is nowhere close to closing, Juniper found that even though Google’s ad revenue is growing, its share isn’t. In fact, Google’s share in 2023 will be 1% lower than it is this year (with an estimated $132.3 billion in global ad revenue). It’s not just Amazon that will claw at Google’s stronghold on the digital ad market; global players like Baidu are also predicted to make an impact on an international stage.

Across all digital platforms, which includes desktop and mobile browsing, in-app advertising, SMS, digital OOH and OTT services, Juniper Research predicts digital will bring in $294 billion this year – meaning it will rise by an average annual growth rate of 15% over the next five years to reach the predicted $520 billion by 2023. The biggest drivers of this growth, according to Juniper, are AI and programmatic advertising.

The key to growth in revenue, says study author Sam Barker, is the power of AI-based programmatic services. “Giving algorithms access to the vast amounts of data generated by advertising traffic, including purchasing habits, user buckets and geographical location, is critical to enabling advertisers to secure a return on their ad spend.”

According to the report, by 2023, 75% of global online and mobile ads will be delivered through AI-based programmatic buys.