Here's the intro to the live version from The Song Remains The Same concert. It's
just a different pattern than the album version.

Standard tuning
                   *                  *               *             *
e------------------3------------------2---------------3-------------2-|
B------------------3------------------3---------------3-------------3-|
G--0h2p0-----0-----0----0h2p0--4p2p0--2--0h2p0-----0--0-------------2-|
D--------4p0-------0----------4----------------4p0----0-----2-----2---|
A----------------2-2--------------------------------2-2--0-2-2-0-2----|
E----------------3-3--------------------------------3-3---------------|
                  *
e-----------------3--------------------------------------------------------|
B-----------------3-1/3-3-3-3-3/7-7-7-7--0h2p0-----------------------------|
G--0h2p0-----0----0-2/4-4-5-4-5/7-7-7-7--------4p0----0-------0---------0--|
D--------4p0------0---------------------------------2-------0---0-----3--3-|
A---------------2-2-------------------------------3-----3p2-------2p1------|
E---------------3-3--------------------------------------------------------|

Then just play around with this chord and slide into the second one while strumming.
e---------|
B--3----5-|
G--0----0-|
D--3----5-|
A--1----3-|
E---------|

Now just play that whole riff again but instead of that ending play this.
e---------x-x------------------------------------|
B---------x-x----------3-3-3-3-----------3-3-3-3-|
G------0--x-x----------0-0-0-0-----------0-0-0-0-|
D----2----x-x----------2-2-2-2-----------2-2-2-2-|
A--3------x-x---0-2p0--3-3-3-3----0-2p0--3-3-3-3-|
E---------x-x-3-----------------3----------------|
repeat as needed.
I also believe those are the same riffs for the first verse as well, with the second ending.

Key:
p=pull off
h=hammer on
x=muted string
/=slide down or up
*above a chord=strum several times