"I still feel there are things I can be doing a hell of a lot better," he told Sydney's Daily Telegraph.
"There is certainly plenty of improvement left in me and that will be my focus heading towards the World Cup.
"I can improve my work at the breakdown, I can improve on ballplaying and I am not happy where my defence is at the moment."
Having shared the Wallabies captaincy with Phil Waugh for the first seven Test matches of this season, Mortlock says he will be honoured if he is asked to lead out his nation at the World Cup.
"It's something that I'd love to do," he added.
"I've done a lot of work to try and improve my leadership, I'd like to think over that time I have matured somewhat.
"I'm on a journey and think I have learned a lot."
Despite speculation that George Gregan may be reinstated as Wallabies captain for the campaign in France, Mortlock is adamant the heated competition for the captain's arm band will not become a distraction.
"If I get the opportunity that would be great," Mortlock continued.
"Whether I'm a captain or not moving forward to the World Cup it won't change my focus and how things are done.
"We have a pretty solid leadership group in the Wallabies and I'm one of the guys involved in that group."