Jessica Breland added 15 points, Allie Quigley had 13, and Sylvia Fowles finished with 12 points and 12 rebounds for the Sky (10-14). Chicago led by 18 points in the second quarter and was up 43-29 at the half.
Atlanta had a 19-2 fourth-quarter run, capped by Angel McCoughtry's free throws with 4:57 left that tied it at 66. Prince made a 3-pointer 21 seconds later to give the Sky the lead.
''We coughed it up at crucial times, but we stuck together,'' Chicago coach Pokey Chatman said. ''It was nice to pull it out against a very good Atlanta team.
''(Epiphanny) is a fifth-year player, someone we trust, and it was nice to see here step up and take that shot, and then get the friendly roll as if we were at home.''
Dream assistant coach Karleen Thompson continued to fill in for head coach Michael Cooper, who is on medical leave after undergoing tongue cancer surgery Thursday in Atlanta. A team representative said Cooper's procedure was successful and that he will return to the bench soon.
''Coop is doing great,'' Thompson said. ''Everything went well. He is going to make a full recovery. We're ready for him to come back, of course, and I know him, he's not ever going to not be thinking of his team.''