The F# chord is G/F#. Hopefully the G chord before the G/F# sounds good to your ears because G/F# is virtually the same as G except you play an F# (root) note instead of a G note, that's all. I presume on a piano it's a case of moving the one finger that plays the G note down one to F#.
e-------------
b-------------
g--0------0---
d--0------0---
a--x------x---
e--3------2---
G G/F#
On a guitar, the 3 here is a G note, the 2 is F#. You see?
I've confused myself. Sorry, C. A piano man will surely pop in and tab you the correct chord.