As a result, Cen Xi was demoted to be a legal officer at Chen Prefecture (郴州, roughly modern Chenzhou, Hunan).
The chancellor Zong Chuke, when an official was sent to examine the governance of the circuit containing those three counties, made the comment, "Do not forget about the three Cens east of the Yangtze River."
It was said that based on Cen's precedent, thereafter family members of officials previously killed during Wu Zetian's reign were able to begin getting promoted.
When the five coup leaders subsequently wanted to submit a petition to Emperor Zhongzong to have the ranks of Wu Sansi and other Wu clan members reduced, initially, no one was daring to draft the petition for them, but Cen Xi, then serving as Zhongshu Sheren (中書舍人), a mid-level official at the legislative bureau of government (中書省, Zhongshu Sheng), was willing to do so, and wrote an eloquent argument for the proposal.
Later that year, after Wu Sansi was successful in having the five coup leaders removed from government, he had Cen made Mishu Shaojian (秘書少監), the deputy director of the Palace Library—an ostensibly honored position that carried little actual power.
Eventually, he was made a deputy minister of civil service affairs (吏部侍郎, Libu Shilang) and was in charge of selecting officials, along with Cui Shi, Zheng Yin, and Li Yuangong (李元恭).
Soon thereafter, before Emperor Zhongzong's death was announced, Empress Wei, as part of the governmental reorganization to consolidate her power, gave Cen Xi the designation Tong Zhongshu Menxia Pingzhangshi (同中書門下平章事), making him a chancellor de facto.
Cen was made You Sanqi Changshi (右散騎常侍, a senior advisor at the legislative bureau) and minister of justice (刑部尚書, Xingbu Shangshu), and later demoted to be the prefect of Shan Prefecture (陝州, roughly modern Sanmenxia, Henan).
Later in 712, Emperor Xuanzong's associates, the chancellor Liu Youqiu and the general Zhang Wei (張暐), with Emperor Xuanzong's approval, planned to kill Cen and two other chancellors aligned with Princess Taiping -- Dou Huaizhen and Cui Shi—but the news was leaked after Zhang informed the plan to the official Deng Guangbin (鄧光賓).
On July 29,[1] Emperor Xuanzong had Wang Maozhong take 300 soldiers to the imperial guard camp to behead Chang and Li Ci.