LOS ANGELES (REUTERS) - Mahershala Ali won the Academy Award on Sunday (Feb 24) for his role in dramedy Green Book as a real-life black pianist who battles racism during a concert tour of the segregated United States South.

It was the second Oscar for the 45-year-old American actor, who took home the supporting actor trophy two years ago for playing a mentor to a young boy in best picture winner Moonlight (2016).

In Green Book, Ali portrays classical and jazz pianist and composer Don Shirley. The film focuses on Shirley's relationship with his white driver, played by Viggo Mortensen, during a 1962 road trip through the US South. Shirley died in 2013.

He won the Oscar despite assertions by some of Shirley's family members that the portrayal of the pianist contained inaccuracies, and the resurfacing of accusations of sexual impropriety by director Peter Farrelly.

Farrelly in January apologised for his actions two decades ago, and Ali has said he respects Shirley's family and has spoken with them.

Ali began his acting career in 2001, appearing as a doctor on television series Crossing Jordan. He played dozens of roles across film, television and theatre before gaining widespread attention as industry lobbyist Remy Danton on Netflix series House Of Cards. When he collected the trophy for Moonlight, Ali was the first Muslim to win an Oscar for acting.

Ali's birth name is Mahershalalhashbaz, which was taken from the Bible and used by the actor early in his career. He decided to shorten his professional name to Mahershala, according to a 2016 story in Vanity Fair, when he was told his real name was too long to fit on the poster for 2012 film The Place Beyond The Pines.

Ali currently stars in his first leading TV role as Arkansas police detective Wayne Hays on HBO series True Detective.