Excellent point. A calendar slam is not a given, even if you go with the assumption that Federer's game would have developed exactly as it did in either era. He would have likely been the dominant guy on clay, IMO, but if you move him up 10 years, then his peak becomes '94-97. Tournament - Champion def. Runner-up (Other two SF's) 1994 Australian Open - Pete Sampras def. Todd Martin (Jim Courier, Stefan Edberg) 1994 Wimbledon - Pete Sampras def. Goran Ivanisevic (Todd Martin, Boris Becker) 1994 US Open - Andre Agassi def. Michael Stich (Karel Novacek, Todd Martin) 1995 Australian Open - Andre Agassi def. Pete Sampras (Michael Chang, Aaron Krickstein) 1995 Wimbledon - Pete Sampras def. Boris Becker (Andre Agassi, Goran Ivanisevic) 1995 US Open - Pete Sampras def. Andre Agassi (Boris Becker, Jim Courier) 1996 Australian Open - Boris Becker def. Michael Chang (Mark Woodforde, Andre Agassi) 1996 Wimbledon - Richard Krajiceck def. MaliVai Washington (Jason Stoltenberg, Todd Martin) 1996 US Open - Pete Sampras def. Michael Chang (Goran Ivanisevic, Andre Agassi) 1997 Australian Open - Pete Sampras def. Carlos Moya (Thomas Muster, Michael Chang) 1997 Wimbledon - Pete Sampras def. Cedric Pioline (Todd Woodbridge, Michael Stich) 1997 US Open - Patrick Rafter def. Greg Rusedski (Jonas Bjorkman, Michael Chang) So, move his prime up 10 years, and for this point's sake, assume he wins Roland Garros from 1994-97. Of the other 12 slams in that span, he would have had to go through Sampras 7 times and Agassi in two others. Not to mention, he may have had to go through both in some of those depending on the draw. It would seem that 1996 would have been the best opportunity for Federer's calendar slam. Sampras was upset early in both Australia and Wimbledon (Kafelnikov won Roland Garros). In all the other years, Sampras and Agassi won 8 of 9 (with Rafter's US Open in 1997 being the exception). There's a reason its only been done once. Consider Sampras - 14 slams, 6 year end #1's. Never won more than 2 slams in a calendar year.