after sampras won his 1st gs title in 1990 he felt alot of pressure to live up to his billing and after the 91 usopen loss he said he even felt relieved that he lost. it also took him 3 years to win a 2nd gs title. by the late 90's chasing the no 1 ranking sampras said the pressure was so great by the end that he took up smoking to calm him down (his 6th no.1 ranking in a row). sampras was clearly after breaking and making records. federer on the other hand bloomed a little later but once he won the wimbledon 2003 there was no looking back, a year and a half later and he's still on a roll stronger then ever. the pressure doesnt seem to get to him i dont think he's playing for the record books i think he enjoys playing more then sampras. he says he'll quit when he's not motivated to play anymore which makes him sound alot like bjorn borg to me. after federer dominates for a few more years and somebody new comes along and beats federer soundly in the gs tournaments mabye he'll retire the way borg did too when he's 25 or 26, thats my theory.