I believe his cocky brother challenged Shang Tsung ahead of the tournament trying to be grand champion. I'm thinking he wanted the "honor and glory" all for himself but bit off more than he could chew.

OR MAYBE you are right... that Liu Kang left the temple and Shang needed a way to convince Kang to come to the tournament.... but if Outworld wanted an easy win, that reasoning would be STUPID because they knew he was Lao's descendant.................................. because Shang obviously already had plans for Sonya; hence her kidnapping and him challenging her for the easy win.