Waymo’s robotaxis will begin carrying passengers through parts of Atlanta on Tuesday in an expansion of a partnership with Uber that began earlier this year in Austin.

Waymo’s driverless march into Atlanta comes just days after Tesla finally launched a limited robotaxi service in Austin, more than five years after CEO Elon Musk brashly promised the electric automaker would quickly overtake Waymo as the leader in autonomous driving technology. Unlike Waymo’s robotaxis, Tesla is initially placing a human in the passenger seat of its rival service to take over the vehicle if something goes wrong.

While Tesla is starting with about a dozen supervised robotaxis, Waymo and Uber have dispatched about 100 completely driverless vehicles in Austin less than four months after their partnership began. The expansion into Atlanta keeps the two companies aligned with a road map they laid out last September.

As has been the case in Austin, Waymo’s robotaxis in Atlanta will be dispatched through Uber’s app. Uber will give customers a choice to request a car operated by a human if they don’t want to take a driverless ride. The robotaxis will initially cover a 65-square-mile (168,00-square-kilometers) area within the Atlanta market before expanding to a larger stretch.

Waymo’s own ride-hailing app is available in Phoenix, Los Angeles and a steadily expanding swath of the San Francisco Bay Area. Factoring in its partnership with Uber, Waymo is currently providing more than 250,000 paid rides per week — making it the early frontrunner in the still-nascent robotaxi market.

But competition looms down the road as Musk continues to insist Tesla’s robotaxi service will be able to grow quickly and Amazon gears up to bring its Zoox driverless cabs to Las Vegas later this year — with plans to expand into San Francisco next year. Zoox is also aiming to bring its robotaxi service to Atlanta, although it hasn’t set a target date for that yet.

Uber once had ambitions to build robotaxis, but reversed course after a bruising legal battle with Waymo, which alleged the ride-hailing company stole its autonomous technology after poaching one of its engineers. After reaching a $245 million settlement with Waymo, Uber eventually sold its self-driving vehicle division following a 2018 crash that killed a pedestrian in Tempe, Arizona.

Uber then pivoted to robotaxi partnerships to remain competitive as driverless cabs reshape the ride-hailing market. “By integrating Waymo’s cutting-edge technology into the Uber platform, we’re continuing to make transportation more convenient, sustainable, and reliable,” said Sarfraz Maredia, who oversees Uber’s efforts in autonomous driving.

With 18 different robotaxi partnerships in place around the world, Uber says it is on pace to make about 1.5 million annual driverless trips that either transport passengers or deliver food.