A pathologist is likely to testify first when Oscar Pistorius's defence team starts calling witnesses at his murder trial next week, a lawyer said.
Brian Webber said the defence plans to start by calling Professor Jan Botha when the trial resumes on Monday after a week's adjournment.
Pistorius had been expected to open the defence case but Prof Botha is likely to be called first because the pathologist has some "personal difficulties", Mr Webber said.
In South Africa, defendants who indicate they will give evidence are expected to go first.
Pistorius and his lawyers say he will testify and explain in court how he killed girlfriend Reeva Steenkamp by accident on Valentine's Day last year. Prosecutors have charged him with premeditated murder.
The Olympic runner says he shot Steenkamp by mistake thinking she was a dangerous intruder who had broken into his bathroom. Prosecutors say the 27-year-old Olympian killed the 29-year-old model intentionally after an argument in the pre-dawn hours.
Mr Webber said: "It is likely that we will call Professor Jan Botha on Monday as he has personal difficulties and I believe that the state has agreed to him giving evidence first."
Pistorius could go to prison for 25 years to life if convicted of premeditated murder.
His testimony is likely to be crucial, with the athlete under intense scrutiny to explain why he shot four times through a toilet door without knowing, in his version, who was on the other side and the location of his girlfriend.
Although some legal experts say Pistorius giving evidence is a risk for his defence, they say he has little choice because he has admitted killing Steenkamp unlawfully and needs to explain his reasons.
Former state prosecutor and now defence lawyer Marius du Toit said: "The only question is whether there was intent and intent is subjective. That means the accused must come and dispel that."
Mr du Toit, who is following the trial but not involved in it, said Pistorius's testimony is "definitely the key".
Mr Webber also said that although lawyers for Pistorius and Steenkamp's family are still in negotiations over a possible out-of-court settlement for her death, nothing would be decided until after the trial.
Representatives of the parties have been in contact since last year. Both sides have declined to give details of any discussions but South African media has speculated that Pistorius might pay Steenkamp's family 200,000 to 300,000 US dollars (£120,000 to £180,000).