Lawyers for professional Zimbabwean hunter Theo Bronkhorst, who led the expedition that killed Cecil the lion, on Monday applied to have the case against him thrown out of court.
The hunt provoked worldwide outrage after it emerged that Cecil was a well-known attraction among visitors to the Hwange National Park and was wearing a tracking collar as part of an Oxford University research project.
Regional magistrate Dambudzo Malunga accepted the court application and remanded the case until October 15 when she said she would determine if Bronkhorst's trial should go ahead.
"The charge is not clear and the circumstances do not constitute a chargeable offence," Bronckhorst's lawyer Perpetua Dube told the court in Hwange, where his trial was due to start on Monday.
Bronkhorst, 52, has been charged with "failing to prevent an illegal hunt" when American dentist Walter Palmer paid $55,000 (50,000 euros) to shoot the lion with a bow and arrow in early July.
Bronkhorst denies any wrongdoing, saying he had obtained all the permits required to kill an elderly lion that was outside the national park boundaries.
He arrived at the Hwange court on Monday wearing khaki trousers, a striped khaki shirt and a grey cap. He declined to speak to reporters.
Prosecutor Namatirai Ngwasha said that "we need time to research and make an informed response to the defence's application."
Palmer, an experienced trophy hunter, was hounded on social media over the killing, and went into hiding after demonstrations outside his dental practice.
He apologised for killing Cecil, a 13-year-old male renowned for his distinctive black mane, and appeared to blame Bronkhorst for misleading him.
Bronkhorst, who was granted $1,000 bail in the Cecil case, was also arrested this month on separate charges of planning to smuggle 29 sable antelopes -- a rare and expensive breed -- into South Africa.
He was also bailed in that case, which will be heard separately.
The owner of the land on which Cecil the lion was killed was listed among five state witness in the trial after initially being charged with allowing an illegal hunt.