With Emperor Xianzong carrying out campaigns to reassert imperial power, Yu became apprehensive, and in or just before 807, he requested that a princess be married to his son Yu Jiyou (). The imperial scholar Li Jiang opposed on the grounds that Yu Di was from Xianbei ancestry and that Yu Jiyou was not even born of Yu Di's wife but of a concubine. Emperor Xianzong, however, saw the advantages of agreeing to the proposal. Around the new year 808, Emperor Xianzong married his daughter Princess Puning to You Jiyou and sent much dowry with her. This surprised Yu Di, who was very pleased. Shortly after, Emperor Xianzong had other officials hint to Yu that he should personally pay homage to the emperor to thank him, a suggestion echoed by Yu Di's son Yu Fang (). When Yu Di went to Chang'an to pay homage to Emperor Xianzong later in 808, he was made "Sikong" () and chancellor, and kept at Chang'an; he was replaced as the military governor of Shannan East Circuit by Pei Jun (). almost to the time he became king