A Lyft car drives along Powell Street in San Francisco, June 12, 2014. Justin Sullivan/Getty Images

Waymo, the former self-driving project of Google, now part of the parent company Alphabet, and ride-hailing service Lyft have forged a partnership to work together on self-driving technology.

The two companies will jointly test autonomous cars on the road, and the development will likely challenge Uber, Lyft’s rival and currently the world’s largest ride-hailing company.

The purpose of the collaboration is to commercialize autonomous driving technology and make it mainstream, starting with pilot projects and product development efforts, according to two sources familiar with the agreement who spoke to the New York Times. While the details were not officially disclosed, both companies confirmed the deal.

Read: Uber Reportedly Tracked & Targeted Lyft Drivers

In a statement emailed to news outlets, including Bloomberg, a Lyft spokesperson said: “Waymo holds today’s best self-driving technology, and collaborating with them will accelerate our shared vision of improving lives with the world’s best transportation.”

There is also no information yet on what the timeline is for any products that may come out of the partnership, or what the exact nature of those products would be.

In an emailed statement sent to various news organizations, Waymo said: “Lyft’s vision and commitment to improving the way cities move will help Waymo’s self-driving technology reach more people, in more places.”

The discussions between the two sides for a potential partnership began in the summer of 2016, during a meeting between Logan Green and John Zimmer of Lyft, and John Krafcik of Waymo, according to the people who spoke to the Times.

The heads of both the companies visited each other’s campuses over the following months, during which time the contours of the deal took shape.

John Krafcik, CEO of Waymo, debuts a customized Chrysler Pacifica Hybrid that will be used for Google's autonomous vehicle program at the 2017 North American International Auto Show in Detroit, Michigan, Jan. 8, 2017. Bill Pugliano/Getty Images

Lyft is the second-largest ride-hailing service in the United States, but the gap between it and Uber is massive, and the rivalry between the companies is very bitter. Also, Uber is among the largest investments of GV (formerly Google Ventures), the venture capital arm of Alphabet, which owns a large share of Uber. But much love has been lost between the two sides.

Read: Two Uber Executives In Waymo’s Lawsuit

Waymo filed a lawsuit against Uber in February, alleging the latter used its self-driving technology after getting a hold of its trade secrets when former Waymo employees joined Uber.

At the time of filing the lawsuit, Waymo said in a statement: “Our parent company Alphabet has long worked with Uber in many areas, and we didn’t make this decision lightly.”

Waymo has been testing its own self-driving vehicles, both on closed tracks and on open roads in the states of Arizona, California, Texas and Washington. The company has also partnered with Fiat Chrysler for testing its technology in a fleet of minivans, and is talking to Honda about testing the technology in Japan. It also started a pilot program in Phoenix, Arizona, offering free rides to people in self-driving Chrysler minivans and Lexus vehicles.

For its part, Lyft has a deal with General Motors that will see autonomous driving technology being tested in Lyft’s network using Chevrolet Bolt vehicles, likely to start in 2018 at the earliest.