Uber and Lyft may be facing their biggest competition to date, and it's not each other this time. It's Google.

While Google's interest in rideshare services is understandable given the search giant been involved in developing driverless vehicles for a few years, Google is a Uber investor, to the tune of $258 million in August 2013. Then there's the fact Google's chief legal officer and Senior VP of Corporate Development, David Drummond, serves on the board of Uber.

According to reports Drummond had reportedly warned Uber that Google may launch a ridesharing service and Uber executives have even reportedly seen screenshots of a ridesharing app being used by Google employees. Uber is supposedly now considering asking Drummond to resign from their board.

Simultaneously Uber announced plans for developing autonomous vehicles through a formidable partnership.

"Uber and Carnegie Mellon University (CMU) are announcing today a strategic partnership that includes the creation of the Uber Advanced Technologies Center in Pittsburgh, near the CMU campus," said Uber in a statement Tuesday. "The center will focus on the development of key long-term technologies that advance Uber's mission of bringing safe, reliable transportation to everyone, everywhere."

Google's move into the ridesharing business would leave Uber without one of its biggest investors, and obviously ignite some contention between the two companies, though in technology many vendors partner even when competing in various segments.

But whether that's the case in this situation, or if all this foreshadows a potential acquisition or buyout of Uber remains to be seen. It may even drive Lyft and Uber into a unified strategy though given the cutthroat business actions by both in the past year that's a bit hard to believe.