Legend of Zelda:Phantom Hourglass HELP

[_Sparkball606_]

Just got this game,and I can't find my Pokemon Pearl, so I started playing this 4 hours ago. I'm still mad at the stupid mouse with the key attached to its tail. If I block an entrance, I still have no success.
So.... Any advice?

I have the word,about 150 green diamond things (weren't they call Preenes or something?), a sword,and full health.

So...How the HEL* do I kill the mouse?When I come running, I accidentally do a somersault instead of my spin slash.

 

[Carl]

You'll notice a moving key, that's cuz a rat has it tied to it's tail or
something, if you try chasing it down it'll run away from you, so how do you
catch him? on the left hole there's a block. pull the block over to the right
hole and plug it up. Stand next to the lock door or as far away from the right
hole as you can so the rat will run out to the other hole but notices it's
pluged up. as soon as it passes the opening to the holes run after it and
use Link's spin attack to kill it, it might take a couple of tries until you
get it. After killing it take the key and unlock the door. follow the path,
kill the keese and exit the cave.

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