The 63-year-old earlier told her lawyers that she had kept quiet about the visit for fear of landing Mr Yettaw or the security guards in trouble.
Ms Suu Kyi said Mr Yettaw left her home at 2345 local time on 5 May.
"I only knew that he went to the lakeside. I did not know which way he went because it was dark," the court heard.
However, the ruling generals say the incident was a stunt designed to embarrass the government.
Ms Suu Kyi - the head of Burma's opposition party, the National League for Democracy - has been held at the Insein maximum security prison in Rangoon since 14 May.
"Thank you for your concern and support. It is always good to see people from the outside world," she told journalists and diplomats before being escorted from the courtroom.
Her trial has been widely condemned around the world as a judicial charade to justify keeping Ms Suu Kyi locked up until after next year's election.
There are signs the authorities want to bring the trial to a swift end.
Ms Suu Kyi's party says her current period of house arrest, which was due to end on Wednesday, was lifted on Tuesday. However, she remains in detention while the trial continues.
Nyan Win, Ms Suu Kyi's lawyer, said on Monday that the prosecution had cancelled the remaining witnesses, so his client would be called to testify even though he had not had the chance for private discussions with her.
Nyan Win said he was "absolutely certain" that the authorities were trying to rush through the trial and that it "could be they have already written the verdict".
There are conflicting reports about whether the Burmese government thinks it has the right to keep Aung San Suu Kyi detained regardless of the trial's outcome.
In a statement, the military said the pro-democracy leader had been under house arrest for only four-and-a-half years of the maximum five years - entitling it to legally extend her detention for a further six months.
But a senior police officer said the authorities had been considering releasing Ms Suu Kyi as a humanitarian gesture before the visit by the US national.
Meanwhile, the Association of South East Asian Nations (Asean) expressed "grave concern" over the situation, a rare move by the group which usually stays out of member states' domestic affairs.
Burma angrily rejected the group's statement, saying it was incorrect and "not in conformity with Asean practice" and accused Thailand, current chair of Asean, of interfering in Burma's internal affairs.
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