Root top-scored with 87 as England batted for a whole day for the first time in the series to close on 247-6 at Adelaide, leaving Australia needing just four wickets on Monday to move into a 2-0 series lead.
"I think everyone's impressed with Joe Root," Warne told reporters. "You can see that there is something about him. He's going to be an England player for a long time because he's a quality player.
"I was hoping that he'd have time down in that five or six position to find his feet and then slowly move up to three - but if he can make three his own, then fine. I still think Ian Bell should bat at three even though Root did well.
"He's going to be a 10-year player plus but give him the best possible chance to do that. I think he could even be a captain, given the way he presents himself. He's very honest, very straight up; there is no fumbling of things, he just gives it to you straight."