An anti-Trump protester crudely interrupted a moving rendition of the US national anthem to yell, "Leave Greenland alone!" before an NBA game being played in the UK. Actress Vanessa Williams was performing "The Star-Spangled Banner" to respectful silence ahead of the clash between the Memphis Grizzlies and Orlando Magic at London's O2 Arena when the heckler -- who sounded American -- loudly shouted his protest. It sparked a wave of boos, before others applauded -- and at least one person was heard shouting "f--k off" as others continued interrupting the anthem.