World number one Novak Djokovic has accepted a role as a goodwill ambassador for the UN Fund for Children (UNICEF).
The Serbian, who grew up during the Balkans war, has already worked with the organisation as UNICEF Serbia ambassador and through his own Novak Djokovic Foundation.
"I am honored to have become a goodwill ambassador for UNICEF, and to continue to help defend and uphold children's rights and provide access to early childhood care and development for every girl and every boy," he said in a statement.
Djokovic has often described tennis as a blessing, one that helped him as a child born in Belgrade in 1987 before the Balkans war broke out.
"The early years of life are crucial," he said.
"When well nurtured and cared for in their earliest years, children are more likely to survive, to grow in a healthy way, to have fewer illnesses, to develop thinking, language, emotional and social skills and become productive and successful citizens of society."
UNICEF deputy executive director Yoka Brandt said helping children was clearly a cause dear to Djokovic's heart.
"He has shown that a powerful voice and powerful actions can make a difference for children, especially when they are very young," she said.
Djokovic's work in his native Serbia through his foundation has helped create more high-quality pre-school education for some of Serbia's most vulnerable children, UNICEF said.