Tennis originated in 1873 when Walter Clopton Wigfield mixed rules of badminton and a Chinese game. Racquets were traditionally wood but steel and aluminum racquets emerged in the 1960s-70s offering more power and control. Tennis can be played singles or doubles on various surfaces including clay, hard, and grass courts. The four Grand Slam tournaments held annually are considered the most prestigious. Notable players include Pete Sampras, Andre Agassi, and Rafael Nadal, the youngest to complete a Career Golden Slam. The Davis Cup is the premier international men's team event, which Spain has won four times.