MELBOURNE, Jan 20 (Reuters) - Australian Open organisers insisted on Thursday their COVID-19 protocols have been "really successful" despite some top players pointing to lax testing at the first Grand Slam of 2022. Frenchman Ugo Humbert has tested positive and world number three Alexander Zverev of Germany believes there is probably more contagion going undetected. read more The tournament director said all players had to test on arrival then again between day five and seven of the Jan. 17-30 competition whose start was overshadowed by the deportation of unvaccinated men"s world number one Novak Djokovic. "On top of that there"s mandatory symptom testing and every single day each player is provided with an antigen kit that they can pick up at hotel or here on site," Craig Tiley told Australia"s Channel 9. "So far it"s worked well and it"s been really successful." However, two-time Grand Slam winner Garbine Muguruza also spoke of slack protocols, saying testing was optional at the Melbourne Park major with results not regularly monitored. "I test every two days by myself in my room," the Spaniard said on Thursday. "It"s not mandatory. I still do it." AUSTRALIA PASSES 2 MILLION CASES Greek Stefanos Tsitsipas, ranked fourth, said it was the athletes" responsibility. "I have been trying to get a few antigen tests and rapid tests to see whether or not I"m positive, which is a responsibility that I have, it"s something that I have to do in order to see if I"m 100%," he added. Australia on Thursday reached 2 million cases in the pandemic, though deaths have been relatively low by international standards at just over 2,900. read more "Right throughout the year, the players have been travelling around the world and there have been protocols they have been following that have enabled them to do that," Tiley added, saying Australia"s protocols were even more rigorous.