Pete Sampras is considered by many to be the GOAT tennis player. Roger Federer might out-GOAT Sampras by the time Fed's done with his career. Currently Fed has 10 GS (grand slam) titles to Sampras' 14 GS.
Despite how well Fed does, Sampras will probably always have the GOAT overhead shot. This is world-class athletic artistry, on the level of Michael Jordan's dunks, or Pele's bicycle-kick goals.
A highlight reel of several overheads
Check this point in a match v Agassi where Sampras has 2 slam-dunk overheads