 Complete the following phrase:  In 1969, the World Snooker Championship became a single elimination tournament, replacing the previous challenge format; this marks the start of the professional games modern era. Six years later, a non-ranking invitational event, the Masters, was introduced; there were 10 competitors in the inaugural Masters in 1975, which later increased to 16 players. John Spencer won the 1975 Masters tournament, becoming the first person to win two Triple Crown events, having won the world championships in 