No Pain No Gain

Without the queen, the Immortals were deemed to lose control over the Zergs, significantly reducing the threat toward humanity. Wang Tong should be able to face Patroclus with abandon by then; otherwise, he would be constantly worried about the fate of humans should he die during the fight. 

Without being able to commit himself fully to the fight, Wang Tong was deemed to be defeated. 

The key to winning the inevitable fight against Patroclus was to find Ark and kill the queen. For the longest time, the immortals had had the upper hand, and leveraging his advantage, Patroclus had forced Wang Tong to reveal a significant degree of his power. He kept a close eye on Wang Tong's every move and every fight, hoping to find his flaws. 

Once Wang Tong located the queen, he would be able to avert the situation and gain the initiative. Otherwise, the terms of the battle, such as when, where, and how the battle would be carried out, were at Patroclus' discretion.