The Demon World Tournament was not a lucky move.The team had an understanding. A plan put together by yusuke,kurama,and hiei.After all had been invited by the 3 kings, they all seized the opportunity to gain intellegence on the 3 kings. This was a huge risk by all of the 3 fighters, requiring them to make drastic sacrifices, if need be in order to make sure the 3 worlds (human,spirit,and demon) avoided war. All three of the fighters were prepared to make these sacrifices. Hiei was prepared to kill mokuro if need be,avoiding a life he had longed for since first being confined to human world.Heie would most likely have won this battle had it happened at the right time.Mikuro's emotions are tied directly to her energy.Which is why she lost against Riasin's friend Natsumi.Hiei had already won her heart in their own twisted way, but would not hesitate to kill anyone who would threaten the life of his sister yukina .Kurama was prepared to fight Yomi. Tho he would have most certainly lost, he atleast would've created an opportunity for yomi to be beaten by the other 3,(yusuke,hiei,and kuwabara.Kuwabara would've sensed that kurama had fallen and sliced through deminsions to avenge his friends death.The powers of the other 3 would've sky-rocketed at the event of kurama's death.And Yusuke was more than ready to kill his demon dad.When they all had learned all they could,Riasin died.If yusuke had gone into the situation blind then he would have listened to his demon dad and sided with mikuro to take down yomi.But yusuke had a different agenda all along. Though the fights were not planned, the 3 fighters gave all they had against demons who would have torn the 3 worlds apart.The same would have remained even if yusuke would have fought mikuro and hie fighting yomi.
Yusuke Denies in his conversation with Koenma, and thus its all conjecture and flimsy conjecture at that.