MELBOURNE, Australia -- A TV commentator has apologized for how he spoke about Venus Williams' play at the Australian Open, saying he was describing her aggressive style as "guerrilla" tactics and not comparing her to a "gorilla."

Former tennis pro Doug Adler said Thursday that he was speaking about Williams' tactics and strategy and "simply and inadvertently chose the wrong word to describe her play."

Adler was doing play-by-play commentary on ESPN for Williams' second-round match against Stefanie Voegele, saying Williams was playing more aggressively after Voegele missed serves. After Voegele faulted on a serve, Adler described Venus as moving in and charging with a "gorilla effect" or "guerrilla effect." Because the words gorilla and guerrilla are pronounced similarly, it's impossible to say for certain which word Adler spoke.

The remark sparked quick reaction on Twitter, with some offended users calling for Adler to be fired for comparing Williams, who is African-American, with a gorilla.