This question already has an answer here:
We are in the combat phase:
- I declared my attackers
- My opponent declared his blockers, stating which attackers he was blocking
- I cast an instant, which automatically kills his blocker. There is nothing blocking my attacker now
Now we're in the damage phase. I said that my attacker now does damage and reduces my opponent's hit points. My opponent said that because my attacker was blocked no damage could be done. I pointed out that the blocker was destroyed before the damage phase, so therefore he wasn't blocking, but he wasn't having it. (My attacker does not have trample)
Is this covered by a specific section in the rules?