In the same year, after defeating Zhang Xiu and Liu Biao, Cao Cao wanted to move on to attack another rival warlord, Lü Bu. Many of his subordinates thought that it was too dangerous. However, Xun You had a different opinion. He believed that Zhang Xiu and Liu Biao had yet to recover from their recent defeat and would not make any further moves. He also pointed out that even though Lü Bu was a formidable warrior and had support from the warlord Yuan Shu, relations between them had recently deteriorated, so it was an opportune moment for Cao Cao to attack Lü Bu. Lü Bu defeated Liu Bei and received help from Zang Ba.