Without the knowledge of Xi Zhicai and Xun Yu among others, Cao Cao secretly contacted Chen Gong, asking him to ambush and kill Lyu Bu on the way to Zhang Yang. At that time, Biang Rang had not yet died, so Chen Gong still had a good relationship with Cao Cao; moreover, with the favor of supporting him, Chen Gong was also very capable, and Cao Cao actually had a great appreciation for Chen Gong.
That was also why Cao Cao, fully aware that supplying Lyu Bu with provisions was like sending a sheep into a tiger's mouth, still did so because he had his eye on the Bingzhou Wolf Cavalry as well as the Eight Valiant Generals under Lyu Bu. While he didn't like Lyu Bu himself, that didn't mean he didn't like his men. He was quite satisfied with Zhang Liao, and he was also very satisfied with the wooden Gao Shun; he appreciated others as well, such as Cao Xing, Song Xian, and Hao Meng, not to mention the more than ten thousand Bingzhou Wolf Cavalry which made Cao Cao even more appreciative.