Mark Webber has not contemplated retirement but he knows it will be a 'very difficult moment' when he does decide to end his Formula 1 career.
Webber will be the oldest driver on the grid when the 2013 season gets underway in Melbourne on March 17, having taken over the mantle following Michael Schumacher's retirement and Pedro de la Rosa's departure from HRT.
Schumacher retired from the sport i 2006 at the age of 36 only to return for a three-year stint with Mercedes before finally calling time on his career last year.
Webber, who is the same age as Schumacher when he first retired, does not want to make the mistake of quitting too early but accepts there is a fine line between carrying on and walking at the right time.
"I haven't been there yet but it is going to be a very difficult moment, no question about it," Webber told GP International magazine.
"I suppose it's just about getting the timing right - not pulling the plug too early, knowing you have more to give of yourself, or going too long and not being quick enough or struggling to do the things you used to be able to do.
"That can become an issue as well."
Webber was linked with a move to Ferrari in 2013 but he penned a new one-year contract with Red Bull.
Despite committing to the team for a seventh season, the 36-year-old has been warned that he will once again be number two to Sebastian Vettel.
Having finished behind Vettel in each of the last four years, Red Bull advisor Helmut Marko expects the German to once again outdo his team-mate in 2013.
"Mark knows what we expect of him. For four years, Vettel and Webber have driven together in our team," Marko told Sport Bild.
"Sebastian was runner-up once and champion three times. The statistic speaks for itself. There is no reason to think the balance of power will change."