David Drummond, the vice president of corporate development at Google's parent company Alphabet left the Uber board in the last few weeks, the Wall Street Journal reports, due to a growing conflict of interest.
Alphabet is an investor in Uber via its venture arm GV (formerly Google Ventures), which participated in a $258m series c round of funding in 2013.
Both companies are ahead in the race to bring self-driving cars to the world's roads.
Google has been testing prototype cars on the streets of San Francisco for some time while Uber is soon to roll out its bookable driverless taxis on the roads of Pittsburgh in the coming weeks, only the second commercial test of the technology in the world.
Drummond said in a statement to the newspaper: “I recently stepped down from Uber’s board given the overlap between the two companies. GV remains an enthusiastic investor and Google will continue to partner with Uber.”