Cat biting on other's neck

I adopt a new male kitten yesterday and my older cat (also a male) seems to be ok with his new companion. There is little hissing and no aggressive fighting. They even touch noses together and follow each other all around. However, my older cat often try to chase the smaller one down, get on his back and bite his neck. Sometimes it's just a minor bite but sometimes it does get rough. I'm really worried that he can injure his friend but I dont know what to do but to separate them. Could someone please give me some advice on how to stop this kind of behavior, please.

Much appreciated.

[Aleda M Cheng, D.V.M., C.V.A]

Separating them is a good idea for another couple of weeks.  You can slowly introduce them for supervised "play dates" beginning with 10 minutes twice daily and gradually increasing over time.  When the older cat becomes too rough you must separate them immediately.  Hopefully the older cat will get the idea eventually, and as the kitten grows larger, the rough behavior will not be as much of an issue.  If the roughness continues even with the time out you will have to use other deterrents such as a water pistol, shaking a can containing pennies as a noise deterrent, or scuffing the rough-houser.