( CNN ) -- Motorcycling star Casey Stoner may have announced his attention to retire from the sport on Thursday , but his apparent lack of motivation to continue racing was not apparent 24 hours later as he topped practice for this weekend 's Le Mans Grand Prix . The two-time MotoGP world champion says he has grown tired of the discipline after five years competing in the elite division , and will bow out at the end of this season -- which still has 15 of the 18 races remaining . `` I will be finishing my career at the end of this season in MotoGP , and go forward in different things in my life , '' the 26-year-old Australian told a pre-practice news conference . `` After so many years of doing this sport which I love , and which myself and my family made so many sacrifices for , after so many years of trying to get to where we have gotten to at this point , this sport has changed a lot and it has changed to the point where I am not enjoying it . `` There are a lot of things that have disappointed me , and also a lot of things I have loved about this sport , but unfortunately the balance has gone in the wrong direction . '' The Honda rider leads the 2012 world championship after two wins from three races . `` It would be nice if I could say I would stay one more year , '' he said . `` But then where does it stop ? So we decided to finish everything as we are now . '' Stoner set a time of one minute 33.74 seconds around the French circuit on Friday , over two-tenths of a second quicker than Spanish teammate Dani Pedrosa . Pedrosa 's compatriot and 2010 world champion Jorge Lorenzo , who is one point behind Stoner in the standings , was almost four-tenths of a second adrift in third position for Yamaha . Seven-time world champion Valentino Rossi was well down the order in ninth , having struggled for form since switching from Yamaha to Ducati for the 2011 season . But despite his recent poor form , the legendary Italian dismissed rumors he was considering retirement and said he wanted to continue in the sport for at least another two seasons . `` For me it 's very difficult to understand where the news starts because I never speak about my retirement , '' the 33-year-old said . `` I want to race in MotoGP for the next two years for sure . ''
Seven -time MotoGP world champion Casey Stoner to retire at the end of this season . The Australian says he no longer enjoys the motorsport as much as he did . The Honda rider tops practice ahead of Sunday 's Le Mans Grand Prix in MotoGP . Two -time title winner Valentino Rossi aims to stay in the sport for the end of this season .