It would depend on the surface...if it was on normal grass in a normal court, Federer would own...if it was on teh plains of Midgar with monsters roaming about then Federer doesnt stand a chance.

Also Sephy would own if they were to have a match in Edge or the ruins of Midgar.

Overall though i think Sephy would win but if the surface is in Federer's favor then Sehpy's huge agility, speed and strength wouldnt stand for anything and he's be beaten into next year.