Disgraced top Chinese politician Bo Xilai has described the testimony given by a former colleague as "self-conflicting" and "illogical".
Wang Zhenggang said he had been present when Mr Bo told his wife to take kickbacks from a construction project in Dalian city when Mr Bo was mayor.
But Mr Bo said only a fool would discuss bribery in front of witnesses.
The BBC reports the scandals involving Mr Bo's family, which used to be one of the most elite in China, have captivated the country.
Mr Bo, who used to be the Communist Party chief in Chongqing, denies bribery and corruption - and also the charge of abuse of office, which the court has not yet examined.
He is accused of using his position to cover up for his wife Gu Kailai, who has been convicted of murdering a British businessman.
Many analysts assume the outcome of the trial, not in its third day, has been predetermined - with a guilty verdict.
But Mr Bo has given what, for China, is an unusually vigorous defence, observers say. They say the court hearing is as much about getting rid of a popular politician as it is about criminal wrongdoing.
Foreign media are not allowed into the trial, but the court in the eastern city of Jinan has been posting regular updates on China's micro-blogging site Weibo (in Mandarin).