To defend against good lobbers you should:
- Be able to hit overheads.
- Volley their lobs in the air from "no man's land" and then move in when you hit another good shot.
- Bring them into the net by using angles and short balls. This will make them reposition.
- Hit to their weaker sides. Most players lob better from the forehand side.
- Hit higher lobs to them for a while.