* You don't control any monsters. If your field is empty, the attacking monster will always attack you directly.
* The attacking monster has an effect that allows it to attack directly. Some monsters have abilities that let them ignore your monsters and attack you directly. This could be a permanent effect or a temporary ability.
* The attacking monster has a special summoning condition that forces it to attack directly. Some monsters have specific summoning requirements that include attacking directly.
What happens when you're attacked directly:
* You take damage. The attacking monster's attack power is equal to the amount of damage you take.
* You can activate some effects. Some cards have effects that activate when you are attacked directly.
* You can use specific cards to negate direct attacks. Some trap cards and monster effects specifically protect you from direct attacks.
Important Note: Being attacked directly is not necessarily a bad thing. It might allow you to activate a powerful card or trigger a strategy that benefits you.
Here's an example:
* Let's say you have no monsters on your field.
* Your opponent attacks you directly with a monster with 2000 ATK.
* You take 2000 damage.
* If you have a card that can negate direct attacks, you can activate it to save yourself.
Overall, being attacked directly in Yu-Gi-Oh! is a common scenario and can be both a threat and an opportunity.