Changing a tire, but the lug nuts are on too tight.?

I need to change my left rear tire, but the lug nuts are on waaaay too tight for me to get off without without power tools. I have recently had this same tire patched, so the shop probably put it back on too tight with an air gun. (Just to check I loosened one of the lug nuts on another tire with no problem.) I have tried WD 40... anyone have any other suggestions?