He has been ranked number one a total of 27 months in his career , the fourth longest , behind only Garry Kasparov , Anatoly Karpov , and Bobby Fischer . He has been ranked number one a total of 27 months in his career , fourth all-time since the inception of the FIDE ranking lists in 1971 behind only Garry Kasparov , Anatoly Karpov , and Bobby Fischer .