Los Angeles (CNN) -- Defense lawyers asked for a delay in the start of Dr. Conrad Murray's involuntary manslaughter trial Friday because, they said, they need more time to answer new theories raised by the prosecution.
Los Angeles County Superior Court Judge Michael Pastor scheduled a hearing for Monday morning to decide whether he will grant the continuance.
Testimony in the trial of Michael Jackson's doctor has been scheduled to start on May 9, with the jury to be chosen next week.
"I'm not saying what I'm prepared to do, because I need to hear and see more information," Judge Pastor said during a Friday afternoon hearing.
The possibility of a delay was raised during a hearing Friday morning when Pastor ruled prosecutors could call new expert witnesses, including one who would testify that there was no way Jackson could have self-ingested the drug that killed him.
Defense lawyer Ed Chernoff said he consulted with Dr. Murray after that hearing and they agreed they needed more time to prepare their expert testimony to counter the new prosecution expert.
"This is precisely the matter I fully expected that was going to happen when the defense said it wanted to go in 60 days," Pastor said.
Murray invoked his right to a speedy trial after January's preliminary hearing in which the prosecution's expert witness admitted he made a math mistake that supported the defense theory that Jackson may have given himself the fatal dose of propofol.
Propofol is a surgical anesthetic that the Los Angeles coroner ruled killed Jackson in combination with several sedatives found in his blood.
"I actually made a mistake on that," Dr. Richard Ruffalo testified during cross-examination, referring to his calculation of the levels of propofol in Jackson's stomach fluid.
Murray's lawyers suggest a frustrated and sleepless Jackson may have poured the surgical anesthetic propofol into his juice bottle while the doctor was out of his bedroom.
A new expert approved by Judge Pastor Friday will testify that he "concludes it was impossible for Michael Jackson to orally ingest" the fatal drug, prosecutor David Walgren said.
"Super expert Dr. Ruffalo prepared a 60-page report," Defense lawyer Michael Flanagan said in court Friday. "We got ready on that, but now the trial in this case will look nothing like the preliminary. I bet you they're not going to call Ruffalo."
The prosecution said the defense is always welcome to call the former prosecution expert.
"They are not calling their original 11 experts," Flanagan said. "They've got three brand new ones, which requires us to prepare all over again for these new theories and justifications of these theories."
The new experts will present "more detailed analysis, but not a new theory," Walgren said.
Judge Pastor said there had been a "massive investment of time and money" put toward the trial and a delay might be expensive. There are 171 potential jurors already "hardship qualified" for the trial, but a delay might require them to go through the process again.