 In 790, there were rumors that Li Na, who governed Pinglu Circuit (平盧, headquartered in modern Tai'an, Shandong), whom Tian Xu's older brother Tian Chao () served under as prefect of Qi Prefecture (齊州, in modern Ji'nan, Shandong), was planning to escort Tian Chao back to Weibo to vie for control of Weibo Circuit.Tian Xu feared this, and, under suggestion by his staff member Sun Guangzuo (), he sent gifts to Li Na to please him and persuade him to send Tian Chao to Chang'an — and further suggested Li Na to accept the surrender of the prefect of Di Prefecture (棣州, in modern Binzhou, Shandong), Zhao Gao (), who had previously submitted to Wang's Chengde Circuit (成德, headquartered in modern Shijiazhuang, Hebei) but who later refused to follow Wang's orders.Li Na therefore accepted Zhao's surrender and took Di Prefecture, despite Wang's attacks.