Mo Farah: How easy is it for celebrities to change their name?
What's in a name? Sir Mo Farah is about to find out.
The four-time Olympic champion has announced he wants to be known as "Mohamed" when he starts the next chapter of his career.
The 34-year-old, who won a silver medal in his last ever track race at a major championships at the weekend, is switching his focus to road racing.
And he's marking the fresh start by ditching "Mo" for "Mohamed".
"My road name is Mohamed," he said.
"I just feel like Mo is done. I need to forget about what I've achieved and what I've done."
Richard Fitzwilliams, a public relations consultant, says he's "very surprised" by the announcement.
"Everyone loves him as Mo," he said. "You would perhaps write Mohamed if you were asked to.
"But Mo - it's shorter and it's also the way he became world famous, and it's how he has run his way into our hearts and minds.
"So (a change) is almost impossible. I think he's looking for something a little more formal. I don't think he probably expects people to actually use Mohamed in full.
"Another reason why he has got a tough task is there are millions of Mohameds - and only one Mo."
But Rebecca May, PR expert and managing director at Alliance PR, says it is possible to change your name and "rebrand".
She said: "Mohamed is not a name change, as such, he just wishes to be known now by his full name, not nickname.
"These intentions appear to reflect Mohamed's next sporting chapter and new career direction. It is the next evolution to his brand. Part of that next step is rebranding.
"Well thought-out and with the right intentions, I would fully support a client under the same circumstances."
William and Ka...Catherine
Farah is not the first famous person to attempt a name change - but some have been more successful than others.
After Kate Middleton's engagement to Prince William, palace officials, members of the royal family, and her fiancé, took to calling her Catherine.
The rest of us stuck with Kate.
Mr Fitzwilliams says this is partly down to newspapers' fondness for nicknames and familiarity.
"In the media, brevity is always preferable, that's why Catherine didn't catch on," he said.
"It's an attempt to be formal when in fact the informal had already taken hold on the popular imagination.
"We still call her Kate. People had warmed to her as Kate, they knew her as Kate."
Manchester United striker Andy Cole decided that, at the age of 28, he wanted to be known as Andrew.
Bearing in mind fans already had a long-standing chant with the original name, it wasn't the easiest request.
Seventeen years on, and the media still haven't quite grasped it - recent newspaper articles show both versions of his name are still being used.
Yet Muhammad Ali had no such problems.
The American boxing legend had already made a name for himself as Cassius Clay, but in 1964 he dropped his birth name after converting to Islam.
Mr Fitzwilliams said: "That's a very good example of where he was big enough to change.
"He was huge, he didn't need marketing. He was a walking brand himself, backed up with all the talent he needed. He was his own mouthpiece."
British singer-songwriter Yusuf Islam also changed his name, but he found Cat Stevens harder to shake off.
He has now incorporated both into his Twitter handle - where he describes himself as "Yusuf Islam the artist also known as Cat Stevens".
Model and TV presenter Katie Price made a concerted effort to rid herself of her glamour model alter ego Jordan.
PR expert Mrs May described it as a "successful and strategic rebrand to mark her new phase from glamour to mother and entrepreneur".
And one celebrity has almost made a career out of changing his name.
American hip-hop star Sean Combs' various incarnations have included Puff Daddy, Puffy, P. Diddy, Diddy and Swag (although the last one was just for a week).
Mrs May said: "P Diddy has the bank account to prove that changing his name has not been detrimental to his journey."
So can Mo pass the baton to Mohamed? His fans - and the world's PR experts - will watch the handover with interest.