Two suggestions I could make here.
1. Try altering the balance on your amp so you hear only the Left or the Right channel. Depending on how the instruments were panned in the studio, you may hear the rhythm guitar more clearly.
2. Download a MIDI file of the song and isolate just the rhythm guitar (along with, perhaps, the drums and Bass).
The latter is one way I've found to identify the chords in a song. Of course, this depends on the MIDI file composer having got it right in the first place. Your ears will tell you.