The appointment of Prince Mohammed bin Nayef as interior minister represents a significant move in the complex political chess game that is being played out in the Saudi royal family.
King Abdullah in a bold and highly unusual manoeuvre effectively sacked Prince Ahmed bin Abdul Aziz, a minister he had installed only a few months ago.
Prince Mohammed, who is in his early 50s, replaces his uncle, Prince Ahmed, less than five months after he took up the post.
A decree said Prince Ahmed - one of the king's half-brothers - was relieved of his position "at his own request".
However observers like RUSI's Michael Stephens believe that Prince Ahmed "did not volunteer his resignation." Mr Stephens described the decision as "surprising."
So why was Prince Ahmed sacked and what does it mean?
"There will be no single reason," Mr Stephens says. The prince had set about removing many senior officials seen as close to Prince Mohammed who had effectively run the ministry for his father Prince Nayef for several years. That in itself was unsettling in a government department which is the largest and most important in the country.
"The people who lost their jobs were the modernisers," Mr Stephens adds. And that would not have sat well with King Abdullah, who has very gradually moved this most strict and conservative of Gulf countries along a more open road.
Equally there is growing concern that young Saudis are crossing the border to join the fight against the Assad regime in Syria.
King Abdullah is highly mindful of the fact that jihadists who had gone to Afghanistan in the 1980s and 1990s had filtered back and created a homegrown militant network, using their military expertise to train a new generation who then went on to attack not just Westerners in the kingdom but the Saudi royal family itself.
A recreation of that jihadist scenario is something the royals cannot tolerate and Prince Ahmed was widely seen as not up to the task of coping with the challenge, nor with growing Shia dissent in the oil rich Eastern Province.
But perhaps the most intriguing aspect to emerge centres around the legacy that King Abdullah wishes to leave.
Abdullah has moved to curb the power of hardline clerics by, amongst other things, limiting the fatwas they can issue.
He ordered a reorganisation of the religious police, installing a moderate as chief in the wake of growing public resentment.
He opened a coeducational university and has given women the right to vote, albeit in largely irrelevant municipal elections. And he has pushed for fiscal reform and more meaningful economic diversification.
But the king is in his late 80s, with question marks surrounding his health, and his putative successor Crown Prince Salman bin Abdulaziz is reportedly ailing.
The Interior Ministry is by far the largest and most powerful in the country.
Mohsen Al Awajy, a Saudi cleric and lawyer with close ties to the Nayef family, says "the ministry is the country, it is the government and the person who runs it is in the most sensitive position in the kingdom".
So Prince Mohammed has been moved by the king into a dominant position on the chess board. What makes the move remarkable in part is his age. He is just 53
"King Abdullah is the first ruler to put qualifications and ability for the job ahead of age," says Mr Awajy.
He adds: "There are some in the royal family who will not be happy but this is a move that is good for the country. It opens a new channel for dialogue and change."
It also opens up the intriguing possibility that the next ruler of Saudi Arabia will jump a generation. The possibility that Prince Mohammed would follow Abdullah is one that Washington would in all likelihood quietly favour.
"The Americans see him as a good operator. They like him," Michael Stephens says, adding: "Mohammed bin Nayef would protect Abdullah's reforms and ensure that the gains are not undone."
America's quiet diplomacy in the Middle East and its push for a gradual transition to more open and accountable societies in a crucial region give Prince Mohammed a strong, if silent, ally.
However, the myriad complexities, competing agendas and sheer size of the Saudi royal family - with more than a dozen princes with claims to Abdullah's throne - means that it is far too early to assume that Prince Mohammed will be the next Saudi king.
But his position on the chess board makes that possibility much stronger now than it ever was.