June 22 (Reuters) - Focus on volleyball at the 2020 Tokyo Olympics: THE ABSOLUTE BASICS * Both men"s and women"s tournaments feature 12 teams divided into two pools, with games played in a round-robin format. The top four from each pool advance to the knock-out phase. * Matches are played to the best-of-five sets, with each set played to 25 points. If a match is tied at two sets each, the final set is played to 15 points. * Teams employ three players at the net and three at the back of the court. Players in the back are not allowed to move to the net to block or spike. * The player in the specialist "libero" position, wearing a different coloured uniform, performs an exclusively defensive role. HOW MANY MEDALS? There are two sets of medals, one for women and one for men. WHAT HAPPENED IN RIO? The Brazilian men"s team defeated Italy in straight sets to win their third gold medal in the sport, with outside hitter Wallace de Souza delivering a barrage of winning spikes, serves and blocks. In the women"s competition, China overcame a surging Serbian team in four sets to take their country"s third Olympic volleyball gold medal. WHAT CAN WE EXPECT IN TOKYO? Brazil and China are favourites to defend their titles. In the men"s event the United States, Poland and Russia will also be in the podium hunt while on the women"s side the United States, Brazil and Serbia are expected to push the Chinese all the way. WHEN IS IT HAPPENING? The men"s competition runs from July 24 to Aug. 7 and the women"s from July 25 to Aug. 8. WHERE IS IT HAPPENING? Tokyo Ariake Arena, a sporting and cultural centre in Ariake district in Tokyo. HOW DID WE GET HERE? The sport was first introduced as "mintonette" by William G Morgan for older members of his YMCA gym in Massachusetts in 1895. It eventually spread globally, leading to the establishment of the International Volleyball Federation (FIVB) in 1947. Volleyball for both men and women became an official Olympic sport at the 1964 Tokyo Olympics. WELL FANCY THAT On Oct. 23, 1964, almost anyone near a television set in Japan tuned in to witness the host country beat the Soviet Union in straight sets for the women"s volleyball gold at Komazawa Olympic Park. Almost 60 years later, the 66.8% audience rating remains the most-watched sporting event in Japanese TV history.