(intro part 1)
E|-----------------|
B|-----------------|
D|----------1-0----|
G|----2-3------3---|
A|-3---------------|
E|-----------------|
(4x)

(intro part 2)
E|-8----0--1--4--8-9-8|
B|------------------------|
D|------------------------|
G|------------------------|
A|------------------------|
E|------------------------|
(play twice after 2nd repetition of intro 1 on another guitar)

(verse 1)
        Fm                                              C
When criminals in this world appear and break the laws that they should fear
        C7                                      Fm              Bbm
And frighten all who see or hear the cry goes out for far and near for

(refrão)
Fm              Ebm                     Fm              Ebm
Underdog        (underdog)              Underdog        (underdog)
Fm                      G#                      Fm              G#
Speed of lighting, roar of thunder, fighting all who rob or plunder
C                       C7              Fm              Bbm   Fm
Underdog        (ooh ooh ooh)   Underdog        (underdog)

(this chord progression is repeated throughout the whole song, except the ending
which goes like this)

Fm                      G#              Fm              G#
Now unleash the dog of wonder, tearing evil souls asunder
C               C7                      C#                                      C#7
Underdog        (bow-wow)               Oh what a wonder-dog    (and how)
                        C       C7              Fm              Bbm7    Fm
Now here's the epilogue (ooh)           Underdog        (underdog)

来源：www.cifraclub.com