Watch a slideshow of Lucinda Williams and Neko Case. Photo by Renee McMahon.Lucinda WilliamsWhere: Main StageWhen: Saturday, 2:45 p.m.When Lucinda Williams is on her game, as she was today (she followed Neko Case onto the stage — if that’s not an alt-country fan’s wettest, hottest dream, I don’t know what is), her shows make you want to be sweating out a fifth of SoCo in 100 degree heat with 100 percent humidity, replacing the whiskey with beer as mosquitoes feast on your booze-soaked blood. Her set was scorching, basically an hour-and-a-half showcase for Doug Pettibone’s seriously underrated, seriously amazing chops on lead guitar, and further proof that the best time to catch your favorite artists is when they’re not supporting an album (although Williams has a new one that’s soon to be released, she drew from it sparingly, with “Hey Little Rock Star” sounding particularly gorgeous). “Essence” and “Joy” were highlights, as was a rollicking cover of AC/DC’s “It’s a Long Way to the Top” to close out the encore.