We watch really interesting times of tennis. Time of great Federer who is No 1 and who is absolute No 2 on the clay. The situation returns me to old disputes here at the forum - is Sampras is the greatest ever with his 14 slams, or say Rod Laver with 2 full Grand Slams 2 consequitive years and 11 slams overall is greater because he won on all 4 surfaces? Probably, Laver is greater. Or say Borg with his 11 slams - 6 times FO champion and 5 times Wimbledon - on absolutely different and controversial conflicting surfaces !!! Many attempts were made scientifically to create some orders in which one could position these greats. It seems to me that our old attempts to give some extra points to a player for winning on different surface MUST PREVAIL. Mathematically we should give for comparison of players much more points ( weights) for winning on different surfaces. In this regard we should divide all slams to 2 categories - ( W+USO+AO) and FO, and winning in both must prevail over bigger number only in 1 category to certaing limits , of course ! I'm here not trying to create new stupid method, not. Today's situation shows us extra information - how difficult to win in both categories. In this regard I have started believe that Borg with 6 FO and 5 W titles is the GOAT. P.S. To the question: "Is Nadal best player on the clay?" my answer is : Probably, not, Borg is unbeatable if u take into account that the man is not only 6 times FO winner, but also 5 times ( consequitive) W champ - unbelievable achievment.