Google is suing Uber for allegedly stealing the technology behind its self-driving cars.
The search giant, which has been working on driverless vehicles since 2009, has filed a lawsuit claiming Uber stole trade secrets and is using them in its autonomous cars.
If the Google lawsuit is successful, Uber could be blocked from using the technology powering its self-driving cars, which are currently being trialled in Arizona.
The brains behind Uber's autonomous car fleet come from Otto, a self-driving truck startup founded by former Google employees, which Uber bought for $680 million (£543m) last year. Google is claiming that before leaving Otto's founders stole designs for its proprietary technology.
"We're taking legal action against Otto and its parent company Uber for misappropriating Waymo trade secrets and infringing our patents," said Waymo, the driverless car division of Google's parent Alphabet. "Our parent company Alphabet has long worked with Uber in many areas and we didn't make this decision lightly.
"However, given the overwhelming facts that our technology has been stolen, we have no choice but to defend our investment and development of this unique technology."
Google alleges Otto's founder Anthony Levandowski, a former Google employee, downloaded reams of sensitive information before his departure and used it to develop his own version.
Otto was founded in January 2016 and had sold to Uber within six months. The ride-hailing company began testing its fleet of self-driving cars less than four months after the acquisition in December last year.
Google said it was made aware of the possible copying when one of its suppliers mistakenly attached machine drawings of Uber's technology in an email.
"Its design bore a striking resemblance to Waymo's unique LiDAR design," Google said.
LiDAR is the radar system Google and Uber's autonomous cars use to build a picture of the obstacles around them.
Uber said: "We take the allegations made against Otto and Uber employees seriously and we will review this matter carefully."
"We found that six weeks before his resignation this former employee, Anthony Levandowski, downloaded over 14,000 highly confidential and proprietary design files for Waymo's various hardware systems," Google said.
"He downloaded 9.7GB of Waymo's highly confidential files and trade secrets, including blueprints, design files and testing documentation."
Google claims other former employees who left to join Otto took further documents.