The threat was buried at the bottom of Elon Musk’s July 20 update to his “Master Plan,” three short paragraphs in a section unassumingly titled, “Sharing.”

“You will also be able to add your car to the Tesla shared fleet just by tapping a button on the Tesla phone app and have it generate income for you while you’re at work or on vacation,” Musk wrote, explaining how Tesla’s vehicles could be used by their owners and lessees once the autonomous era truly arrives. “This dramatically lowers the true cost of ownership to the point where almost anyone could own a Tesla.”

Automakers have spent this year aligning themselves with ride-hailing companies as they brace for a future in which traditional car ownership gives way to ”shared mobility.” General Motors invested $500 million in Lyft, and bought up the remains of Sidecar. Volkswagen put $300 million into Gett. Toyota pledged an undisclosed sum to Uber. BMW, Fiat Chrysler, and Daimler also have ride-hailing partnerships.

That Tesla also wants to get in on ride-sharing isn’t new or particularly surprising. The big announcement came next:

“In cities where demand exceeds the supply of customer-owned cars,” Musk wrote, “Tesla will operate its own fleet, ensuring you can always hail a ride from us no matter where you are.”

While automakers and tech companies have been eager to describe the autonomous future—streets traversed by vehicles that whisk their passengers to destinations at the touch of a button—they have deliberately avoided the question of ownership.

Asked by an analyst last year during Tesla’s second quarter earnings call whether the company intended to supply “cars to ride-sharing firms” or “cut out the middleman and sell on-demand electric mobility services directly,” Musk responded, “that’s an insightful question … I don’t think I should answer it.” Asked again by the same analyst the following quarter, he said, “Still no comment … I think there’s a right time to make announcements. And this is not that time.”

The time, apparently, was Wednesday, when Musk published his “Master Plan, Part Deux” stating that Tesla would “operate its own fleet” in the absence of individuals who own or lease the cars.

It’s almost certainly a blow to Uber. Travis Kalanick, the company’s CEO, has reportedly said that he would happily buy all of Tesla’s projected autonomous output for 2020 if that were an option. More importantly, though, it signals that there’s another company with Uber’s resolve, tech savvy, and go-it-alone attitude bent on capturing a share of the ride-hailing market.

Tesla will make cars. Tesla will sell cars. Tesla will also manage ride-hailing cars. Even Uber—whose $62.5 billion valuation is largely staked on the self-driving future—hasn’t made its vision that clear yet.