time in New York City where they grew close to Sabicas and Mario Escudero, playing together into the night. 1970s De Lucía made a cameo appearance, dressed as a Mexican guitarist, in the 1971 western Hannie Caulder, playing the melody of Ken Thorne's main theme over a string section. That year, he released the album El mundo del flamenco, which included a version of Mario Escudero's "Ímpetu", a bulerías. Guitar International mentioned his "very aggressive" approach to playing "Ímpetu". Escudero was a major influence on de Lucía during this period, inspiring him to explore new possibilities for flamenco. He began working with record producer José Torregrosa. De Lucía's 1972 release El duende flamenco de Paco de Lucía was considered a groundbreaking album in the flamenco community. As the 1970s progressed, de Lucía continued to produce groundbreaking albums and ventured into an increasingly unconventional and innovative style of flamenco with jazz influences. His next release, Fuente y caudal, acclaimed particularly for his "Entre dos aguas", which has become arguably his best-known composition, and also for "Solera" and "Cepa Andaluza". "Entre dos aguas", a rumba featuring bongos with an electric bass, means "Between two waters", referring to his home town of Algeciras, where the Mediterranean meets the Atlantic. Biographer Pohren describes "Cepa Andaluza" as a "phenomenal" bulerías, which is "accompanied by palmas, shouts of encouragement and general jaleo, and makes one want to leap up and dance." The album also features several other tracks named after Andalusian landmarks, a theme de Lucía continued in his later albums. The Fuente y caudal album was one of the best-selling Spanish records for several months and de Lucía and Torregrosa found that the additional instruments and approach away from traditional flamenco proved more popular with the general public. The early influences of the traditional players became increasingly less apparent as de Lucía embraced jazz and other influences, creating his own voice and distinct style, yet never venturing too far from his roots. On 18 February 1975, de Lucía became the first-ever flamenco performer to perform at the Teatro Real of Madrid. He played a set with his brother Ramón, in front of a relatively young audience without the use of effects. Pohren said that de Lucía's performance "was brilliant technically, and played a meaningful, moving, traditional brand of flamenco that did not betray what Paco had in store for the flamenco guitar in the future."