NEW ORLEANS — Warriors head coach Steve Kerr said David Lee will be active and available in an emergency situation for Saturday’s Game 4, after the power forward missed the first three playoff games with a sore lower back. Lee participated in a three-on-three scrimmage after Friday’s practice and responded well at Saturday morning’s shootaround — a far cry from where he was five or six days ago, when his back was locking up and spasming. Most importantly, I’m back to feeling like, if Coach needed me tonight, I could come in and give us some minutes. Memphis plays Portland late Saturday with a chance to take a 3-0 lead in the best-of-seven, first-round series. The Grizzlies start a tough frontline in Marc Gasol and Zach Randolph and often stay big with reserve center Kosta Koufos, which could lead to playing time for Lee. The two-time All-Star has kept a good attitude all season, despite seeing his starting role and customary minutes taken. Warriors backup point guard Shaun Livingston believes the players have gotten the message.