MADRID—Manuel Santana, one of Spain’s greatest tennis players who helped to popularise the sport in the country, died on Saturday aged 83. Santana, four times a Grand Slam champion, died at his home in Marbella, southern Spain, the Madrid Open, a tournament of which he was honorary president, said in a statement. Santana became world number one in 1966, the same year that he won Wimbledon. The previous year, he had won the U.S. Open and led Spain to an upset victory over the United States in the Davis Cup final. He also won Roland Garros in 1961 and 1964. Coming from a humble family at a time when tennis was considered a sport only for the upper classes in Spain, Santana became a stalwart of the country’s Davis Cup team, amassing a 69–17 win-loss record in singles between 1958 and 1973. He also won the tournament at the 1968 …