Starting a new job is never easy. This is true for anybody, even Dara Khosrowshahi, the new chief executive of Uber who has an unenviable task on his hands.

Just over a month into the job and Khosrowshahi is dealing with a regulatory headache in London, one of its biggest markets, and an episode of "Game of Thrones" within his own company.

On Tuesday, Khosrowshahi will meet with London's transport authority, Transport for London (TFL), to try and convince the organization to renew Uber's operating license in London which expired on September 30. It can continue to operate until the appeals process is exhausted.

Overturning the ban in London will be Khosrowshahi's biggest test to date. He will need to show Uber is a grown up, mature company, that can talk to authorities and adhere, or at least help shape regulation. Uber's traditional approach has been to come into a market, and deal with the regulation later. That is catching up with the company.

The way Khosrowshahi handles the London issue will give us an idea of the kind of the CEO he can be. Will he be confrontational or understanding of the market? Former CEO Travis Kalanick often proved to be abrasive in these situations. Khosrowshahi will need to show he is different because he is on a drive to clean up the corporate governance of the world's most valuable start-up.

But Khosrowshahi has a thorn in his side that just won't go away – Kalanick. The ex-CEO appointed two new people to Uber's board, a move that took Khosrowshahi by surprise and that he denounced as "disappointing" and "unusual." Kalanick did this because the board is set to vote on reforms that would limit his power. Two new board seats picked by him could give him some allies.

Just as Cersei Lannister in "Game of Thrones" went to the Iron Bank for help with her war, Kalanick has tried to get allies of his own to keep him in power. Khosrowshahi has a problem, because while he is dealing with the issues in London, Kalanick's moves at home threaten to derail his push to clean the company up.

What Uber doesn't need is a messy boardroom war, especially amid reports that SoftBank could invest several billion dollars in the ride hailing app. Having SoftBank on board would give Uber serious financial clout that could help it crush competitors. Also, an initial public offering in 2019, which could be on the cards if investor Goldman Sachs gets its way, could give early investors the liquidity they want.

Any potential power struggle or war in the boardroom could threaten all of this. Khosrowshahi's leadership is set to be tested. He will need to balance the needs of a number of conflicting parties while making sure he can continue to lead from the front.

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