Paul Annacone has confessed to The Tennis Space which is impossible to say if the best Federer would beat the best Sampras: "I can’t know what would have happened if Roger had played against Pete in top form. When people make these comparisons it makes me laughing. I consider myself a tennis expert, but we can’t in any way to compare two totally different eras together. I feel emotionally frustrated when people offer opinions like that. If Pete had played in 2012 against Rafa or Novak maybe something would change in his game.
" And again: "But I believe that the best players are large apart from the time they play, and we can’t predict what he would do against Roger Laver.
Who knows? Every decade has its rivalries, I got to sit in the front row and watch the big matches between Agassi and Pete. Often I hear saying that Agassi never lost to Nadal on grass, and I think “Why? How can you be sure?” or that Borg never lost to Rafa on earth. “I do not understand how you can say these phrases.
The technology is different. Who knows what Borg was strong with these new shoes?" Annacone claims that it’s impossible to say who’s the best ever: "They made lists that include the top 20 greatest players in tennis history. It’s a fun game but we can’t definitely say Roger is the number 1, the number 7 or 4 as we can’t do with any player. Of course, the number of losers Slam gives you an indication of what a player has been able to do, but to establish a ranking is totally different. "