Answer
Nguyễn Phú Trọng was the General Secretary of the Communist Party of Vietnam when Trương Tấn Sang was President. Trọng was elected as the General Secretary in 2011 and Sang was elected as the President in 2011. Trọng and Sang both served in their respective positions until 2016, when Trọng was re-elected as the General Secretary and Sang was succeeded by Trần Đại Quang as the President.