Why virat kohli is not in second test match versus South Africa?

Virat kohli is not a part of the squad against South Africa in second test match because of injury in upper back spasm without virat kohli it will be difficult for indian team to beat South Africa but kl Rahul will be leading the side replacing virat kohli kl rahul is in good touch let's hope he will manage this good form in second test match continuosly.Lets hope can manage to win the match and series against South Africa.

Also Read :- When will second test start?