About Zhang Jike's injury, he did not get injured during the national championships. Actually he injured his back during practice one week before the World Cup, and had to have an injection to stop the pain in order to play. He still felt numb in the back after arriving in the World Cup, and Liu Guoliang was so concerned that he called doctor in China seeking advice about Zhang Jike's condition. The doctor said that if Zhang Jike was not improving then maybe he should not play at all. But Zhang Jike persevered. He later said that if he did not want to play, he would not have come in the first place. He had the injection because he was determined to play the World Cup no matter what. If you watch his game with Timo Boll, you will notice that he was having trouble with his back.
Before the national championships starts, we thought that he would not play in any events, teams or singles, like Li Xiaoxia did. But he played in the team event and men's double anyway. He withdrew from the men's singles because he did not want to aggravate his injury from which he has not fully recovered. If he withdrew from the team event and men's double, the team or Ma Long would be affected by his withdrawal. As for men's single's, he's the only one that would be affected due to withdrawal.
It's not unusual for Chinese top players to withdraw from the single's event in order to reserve energy for other events. For example, in 2012 national championships, Ma Long helped Beijing Team to win the men's team champion and paired with Ding Ning to win the mixed double champion. But after having a bye in the first round, he withdrew from men's single's event in the second round (Round of 32).
