任圜
In 925, Li Cunxu launched a major attack on Later Tang's southwestern neighbor Former Shu, putting his son Li Jiji the Prince of Wei in titular command of the operations but with his chief of staff Guo Chongtao in actual command. Li Yu volunteered for duty on this campaign, and he and Ren Huan were made chief strategists on Guo's staff. On the campaign, Later Tang's army ran into initial difficulties with terrain, but Li Yu advocated quick advancement, as he believed that Former Shu's emperor Wang Zongyan had lost the faith of his subjects due to his frivolous rule, and a quick advancement will cause Former Shu's morale to collapse. Guo agreed with him and ordered quick advancement. On the campaign, Li Yu was also in charge of military correspondences. After the Later Tang army conquered Former Shu later in 925, Li Yu, for his contributions, was given the additional office of "Zhongshu Sheren" (), a mid-level official at the legislative bureau (中書省, "Zhongshu Sheng").