Veteran free-agent point guard Derek Fisher has agreed to sign with the Dallas Mavericks, coach Rick Carlisle told reporters Wednesday night. The 38-year-old Fisher finished up last season with the Oklahoma City Thunder, but had not signed with anyone this season. The Mavericks need help at point guard as starter Darren Collison was sidelined Wednesday with a finger injury, and Dominique Jones made just his third career start. "Right now, the point guard position is a challenge for us," Carlisle said, according to ESPNDallas.com. "I think Derek can help us." Fisher averaged 5.6 points and 2.7 assists in 63 games with the Lakers and Thunder last season.