Moto GP championship leader Casey Stoner dominated his rivals in the first day of practice at the Australian grand prix on Phillip Island on Friday. But the 25-year-old Australian, who has had a four-year love affair with the picturesque seaside circuit 140 kilometres (90 miles) south of Melbourne, criticised the state of the track. Stoner is aiming for his fifth successive Australian grand prix, a result that would make him virtually unbeatable in the championship race. He quickly showed why he is the hot favourite for Sunday\'s race as he finished the morning practice session almost three tenths of a second ahead of nearest rival Jorge Lorenzo. Stoner set the quickest times in both 45-minute sessions, with his overall fastest time coming the first time around (1:30.535). The Honda rider, who won his only previous championship in 2007 on a Ducati, later said the track had deteriorated over the past 12 months. \"It\'s always been a little bit bumpy into turn one and maybe one or two other small bumps, but this year they\'re a lot more aggressive than they were in the past,\" Stoner said. \"For such a fast track it\'s really scary. \"I\'m not too happy with the condition of the track -- I don\'t know what they\'ve been racing around here but it\'s made the track a lot worse. \"One or two metres out from the curb it seems to be really, really bumpy.\" Stoner\'s only rival for the Moto GP title, defending champion Jorge Lorenzo, was almost three tenths of a second back in second spot, with Italian Marco Simoncelli a further two tenths of a second behind in third. German Stefan Bradl set the pace in the Moto 2 category with a leading time of 1:34.039 in the morning session. Bradl crashed towards the end of the first practice and was not able to better his time, but no other rider was able to match the German, San Morino\'s Alex de Angelis coming closest 0.122 seconds behind. Italian Andrea Iannone was in third, just over half a second behind Bradl. Germany\'s Sandro Cortese led the 125cc class with a time of 1:38.530 ahead of Spaniard Nicolas Terol (1:38.708) and France\'s Johann Zarco (1:39.104).