MANILA (Reuters) - When Philippine leader Rodrigo Duterte visits China this week, he'll need to salvage something from a "pivot" to Beijing that has left him empty-handed, and exposed his neighbours to a new level of brinkmanship in the South China Sea.

Despite his huge domestic popularity and great affection for China, Duterte is under growing pressure to push back at its growing maritime assertiveness. After avoiding the issue for three years, he has vowed to raise with President Xi Jinping a 2016 arbitration ruling that invalidated China's claim to sovereignty over most of the South China Sea.