Federer came to picture when Sampras was in good form. He had to contend Sampras and Agassi initially and then had to fight the likes of Roddick, Nadal etc. Remember nobody has won titles with the consistency he has won and he has one of the best all round games. Sampras was very good player but his record in clay is questionable same can be said about becker, edberg. Ivan lendl was very good in all surfaces except Grass, Borg never won Aus or US open, Mcenroe never won French. The overall quality to play in all surfaces is something gifted and very few players have that (Agassi, Rod laver) and fedex is one among them. Nadal or Roddick or Even Nalbandian are extremely gifted and talented players, but when they play federer they look pedestrian not because they are not good, but Federer is too good.