Saudi Arabia's new Crown Prince Mohammed bin Nayef, appointed by royal decree on Wednesday, has waged war against al Qaeda and survived a suicide bombing claimed by the jihadists.
King Salman said Mohammed, 55, will also be deputy prime minister and remain interior minister and head of the political and security council, a coordinating body.
The removal of Prince Moqren bin Abdul Aziz bin Saud as crown prince leaves Mohammed as the first of the second generation, or grandsons of the kingdom's founder, Abdul Aziz bin Saud, in line to lead the conservative Islamic kingdom.
Born on August 30, 1959, Mohammed became interior minister in 2012, taking over from his late father Nayef bin Abdulaziz who headed the strategic ministry for 37 years.
He was the youngest Saudi royal to be named to such a high-ranking post, in a country where key figures are often advanced in age.
He oversaw a crackdown on al Qaeda following a wave of deadly attacks in the Gulf state between 2003 and 2006.
Mohammed studied politics in the United States and had several military training courses, including under the aegis of the CIA, according to experts on the Saudi royal family.
In 1999, the bespectacled Mohammed was given his first official post, serving as aide to his father.
His formative years at the interior ministry allowed him to build a "solid network both inside Saudi Arabia and regionally to fight al Qaeda", said one Saudi expert, speaking on condition of anonymity.
Western governments noted his "successes" in confronting the global extremist network and his men were the first to detect and prevent al Qaeda attacks, said one expert.
The prince's reputation put him in the firing line and nearly killed him.
He survived an attack by the Yemen-based al Qaeda in the Arabian Peninsula in August 2009 when a suicide bomber managed to infiltrate his security.Mohammed suffered only superficial injuries when the bomber killed himself.