Brazilian tennis player Marcos Daniel is at the centre of an investigation by Australian Open officials after an alleged fracas involving a woman spectator last night.

The tournament referee ordered the inquiry after the alleged incident between 31-year-old Daniel and the spectator following his first round loss to Colombia's Alejandro Falla.

Colombian fans stand courtside after an altercation with Marcos Daniel. Credit:Reuters

"The tournament referee's office is looking into the alleged incident," a Tennis Australian spokesman confirmed.

understands Daniel had an altercation with Colombian spectators, and that the woman was caught in a disagreement between the player and her brother.