Unless you are sure you are going to win, don't bother looking.

If you are determined, and it wasnt long ago, the battle report maybe still in your logs,if so, find it and open it, it should tell you the present location of the town of the player that hit you.

If you are still interested, once you have clicked in the "i" next to the player's picture it will open up and give you his current location. You can also add him to your Contacts list for future reference.