Lou Cheng was sure that Liang Yifan would target his left shoulder. considering that his injuries hadn't fully recovered. If he didn't consider this and take the easiest approach, others would doubt the genuinity of his super-class status.
Because of this, Lou Cheng had thought specifically about how to deal with this problem. He wasn't a deity of legends and couldn't possibly remove this weakness by recovering from the shoulder injury immediately. So if Liang Yifan continued to attack this spot, it would be a matter of time before Lou Cheng gave an opening and lost the match.
This was an outcome that both parties could agree on silently.
The only way around it would be to set traps based on this weakness. Before the real problem emerged, Lou Cheng wanted to use a false image to hook his opponent so he could deal a heavy blow and win the match directly, or at least get the upper hand.
