Pancho Segura, a top-quality tennis player for many years, was born Francisco Olegario Segura in Guayaquil, Ecuador, on June 20, 1921, but moved to the United States in the late 1930s and is considered to be an American tennis player. He was a small man, no more than 5'6" (1.68 m), with badly bowed legs from the rickets that he had suffered as a child, but he made up it for with extremely fast footwork and a devastating two-handed forehand that his frequent adversary and the future tennis impresario Jack Kramer once called "The greatest single shot ever produced in tennis".

By the time he was 17 Segura had won a number of titles in Latin America and was offered a tennis scholarship at the University of Miami. He won the Intercollegiates for three straight years, in 1943, 1944, and 1945, and was also the number 3-ranked American player during those years. He won the U.S. Indoors in 1946 and U.S. Clay Courts in 1944 but was never able to win the national championship at Forest Hills, although he reached the semi-finals a number of times.

Long before Open Tennis, Segura turned professional in 1947 and was an immediate crowd-pleaser with his winning smile, infectiously humorous manner, and unorthodox but deadly game. Although he was overshadowed as a player by Kramer and Pancho Gonzales in his professional career, he won many matches against the greatest players in the world and was particularly brilliant in the annual United States Pro Championship. He won the title three years in a row from 1950 through 1952, beating Gonzales twice. He also lost in the finals four times, losing to Gonzales three times and once to Butch Buchholz in 1962 when he was 41 years old.

After retiring from the Tour, he became a teaching professional for many years in Southern California and is widely credited with helping form the young Jimmy Connors.

He was inducted into the International Tennis Hall of Fame in Newport, Rhode Island, in 1985.

• List of male tennis players