1) Do nothing with the rhythm guitars when the lead guitar comes in and make the lead louder than it should be
2) Automate to slowly reduce the volume of the lead and rhythm guitars after a few seconds until everything is "right" again.
3) When the lead guitar ends, emphasise the next riff by making the rhythm guitars louder than it should be and then reduce the volume again
That way you direct the listener's attention towards the lead guitar by making it pop out and to the rhythm guitar after the lead is done.
Even mixes are horribly boring. Don't make them!