word choice - "One of my friends" vs. "one of my friend"

Which of the following is correct?

1. Yesterday, I met one of my friends.


2. Yesterday, I met one of my friend.

Answer

It's "one of my friends". The other option would be ungrammatical.

To spice it up a little, here are the stats from the Corpus of Contemporary American English and the British National Corpus:

                     COCA    BNC
one of my friends     251     40
one of my friend        0      0
one of your friends    58      6
one of your friend      0      0
one of our friends     40      7
one of our friend       0      0
one of his friends    182     60
one of his friend       0      0