José Javier "Chucho" Acasuso (born October 20, 1982 in Posadas, Misiones) is a professional male tennis player from Argentina. Like many of his fellow countrymen, he favours clay. He is known for his strong serve and his hard groundstrokes off both sides. His clothes sponsor is Topper and his racquet sponsor is Head.

Acasuso began playing tennis at the age of two, when his father took his brother and sister to his grandfather's tennis club. Reportedly, he got the nickname of "Chucho" from the fact that, when he was a child, he used to say his name was "José Acachucho." Acasuso played both basketball and tennis up until the age of 12, and then gave up basketball for tennis. Like Carlos Moyà, Acasuso is a natural left-hander, but plays tennis right-handed.

Acasuso turned professional in 2000, playing futures and challenger events. In 2001, he made an immediate impact in his first ATP tournament in Buenos Aires, where he defeated former No. 10 player Félix Mantilla in the last round of the qualifying to make the main draw, and then defeated compatriots Franco Squillari in the quarter-finals and Gastón Gaudio in the semi-finals. However, he lost to then-number-1 player Gustavo Kuerten, 6–1, 6–3. Later in the year, he won his first challenger event in Bermuda and finished the year ranked at 86 in the world an improvement of 89 places from the previous year.