Yan Liang
Guan Yu's biography in the "Sanguozhi" mentions that Yuan Shao ordered Yan Liang to besiege Cao Cao's general Liu Yan (劉延) at Boma. Cao Cao then sent Zhang Liao and Guan Yu to lead the vanguard force to attack Yan Liang. During the battle, Guan Yu spotted Yan Liang and charged through enemy lines towards him, killed him and took his head. Yuan Shao's other generals were unable to resist the assault and the siege on Boma was thus lifted. Yuan Shao's biography in the "Sanguozhi" mentions that after Yan Liang's death, Yuan Shao's army crossed the Yellow River to the south of Yan Ford (延津; north of present-day Yanjin County, Henan), where he sent Liu Bei and Wen Chou to attack Cao Cao. They were defeated and Wen Chou was killed in battle (nothing is mentioned about him being slain by Guan Yu). Yuan Shao launched another attack but was defeated again and his generals were captured by Cao Cao.