Depends on the current elo.
The system is a bit slow to update ranks automatically.
If you have 1620 and your rank is 1000
Your oponent have 1621 elo and is rank 1200
If you beat your oponent you will most likely get moved up two positions "998"
If your oponent beat you, he will attain your old rank of 1000, and you will be placed in the rank that fits your elo on the ranking lists.
Correct me if im wrong other nerds.