The Saudi royal family now faces the challenge of lining up a second generation of princes as potential heirs to the throne after the death of two aging crown princes in just eight months, analysts say.
On Monday, Defence Minister Prince Salman bin Abdul Aziz, 76, succeeded his late brother Prince Nayef as the Gulf oil powerhouse's crown prince and heir.
Nayef died on Saturday aged 79 in Switzerland, only eight months after becoming heir apparent after the death of his brother crown prince Sultan at the age of 86.
State television Al-Ekhbariyah said King Abdullah appointed Salman "crown prince and deputy prime minister" while keeping him as defence minister, adding that Prince Ahmed bin Abdul Aziz would take over from Nayef as interior minister.
Analysts said Salman's appointment as heir was expected, but the real challenge now facing the royal family is the transition to the next generation.
"This is the most important thing -- the transition to the next generation of leaders," said Eleanor Gillespie, a contributing editor of the London-based Gulf States Newsletter.
"The need to name a new crown prince for the second time in a year highlights the flaws in a gerontocratic system," she said.
Jane Kinninmont from London's Chatham House said naming the second deputy premier -- the unofficial second in line to the throne -- is the challenge.
"Choosing the second in line to the throne, which is not a formal position but is likely to be signified informally by the title of second deputy prime minister, is more challenging," said Kinninmont, a Middle East and North Africa senior research fellow.
King Abdullah had in 2009 appointed Nayef, the long-serving interior minister, as second deputy prime minister, a position he kept vacant since his accession to the throne in 2005.
Five of the sons of king Abdul Aziz, the founder of Saudi Arabia, have acceded to the throne since 1953, with 18 sons still alive.
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Salman is one of four remaining brothers of the strong "Sudairi Seven," the formidable bloc of Abdul Aziz's sons by a favourite wife, Princess Hassa al-Sudairi.
In addition to Salman, remaining Sudairis include Prince Abdul Rahman, Prince Turki and Prince Ahmed, deputy interior minister who succeeded Nayef as the kingdom's security chief.
The monarch in 2006 established the Allegiance Council, a commission of 35 senior princes, as a new succession mechanism whose long-term goal was to choose the crown prince.
But this mechanism is not likely to be activated while the ailing Abdullah is alive.
Saudi columnist Jamal Khashoggi argued that "seniority is important in the royal family" when it comes to who gets to stand in line for the throne.
He added that "those who hold strong government posts among the first generation should be seen as traditionally having the right to succession."
He pointed out that some of the grandsons of Abdul Aziz, who are seniors among the second generation, are older than their uncles, naming Prince Khaled of Mecca, son of the late king Faisal.
"There are a group of younger candidates currently raising their profiles," Gillespie said.
Disputes within the Al-Saud dynasty mostly remain out of the public eye, and consensus within the family appears to be holding strong amid the turmoil currently sweeping the Arab world.
"The need to achieve some measure of consensus among senior princes is probably the main source of checks and balances on the Saudi ruler's power," said Kinninmont.
"This also means the likelihood of radical change in policies is limited," she added.
In the meantime, Salman, who did not occupy a ministerial post until succeeding his brother Sultan as defence minister last year, is seen as the most experienced among his brothers after serving as Riyadh governor for nearly 50 years.
It was a job "that allowed him to serve as a generally very well respected arbiter of Al-Saud family affairs, as well as overseeing the city's emergence as Saudi Arabia's capital," Gillespie said.