Apple has invested $1 billion in China’s ridesharing service, Didi Chuxing. The move will help Apple better understand the important Chinese market, according to a Reuters interview with Apple CEO Tim Cook.

This means that Apple is aligning itself with Uber’s chief rival in China. The Chinese ridesharing market may seem way out of Apple’s current business, but Apple is rumored to be working on a self-driving car, and ridesharing companies could be a key part of the driverless car future.

In the meantime, Apple is also trying to reinvigorate its sales in China, where Cook is currently traveling. Cook told Reuters that he saw opportunities for Apple and Didi Chuxing to collaborate in the future.

“We are making the investment for a number of strategic reasons, including a chance to learn more about certain segments of the China market,” he told Reuters. “Of course, we believe it will deliver a strong return for our invested capital over time as well.”

The funding is the largest ever raised by Didi Chuxing, formerly known as Didi Kuaidi. The ridesharing service says it completes more than 11 million rides per day.