Chinese politician Bo Xilai has said that he was framed and that he only admitted to one of the bribery charges against him under interrogation.
The 64-year-old former Communist Party chief of Chongqing has been charged with illegally taking almost 27 million yuan (€3.3m), corruption and abuse of power and will almost certainly be found guilty.
Mr Bo's denial of one of the charges and strong language as he made his first public appearance since being ousted early last year were unexpected.
But at least one observer said he could have struck a deal with authorities to show he was getting a fair trial in exchange for a pre-arranged sentence.
President Xi Jinping is seeking full support from the Communist Party as he seeks to push reforms that will rebalance the economy, and will want Mr Bo's trial to be finished quickly.
"He (Mr Bo) is clearly going along with this trial," said Nicholas Bequelin, a researcher for New York-based Human Rights Watch.
"The outcome has been already decided. There's probably an agreement already between Mr Bo and the party as to what the outcome will be."
Mr Bo's downfall has pitted supporters of his Maoist-themed egalitarian social programmes against the capitalist-leaning economic road taken by the leadership in Beijing, exposing divisions within the ruling party as well as Chinese society.
Mr Bo was one of China's rising political stars and his trial in the eastern city of Jinan marks the country's biggest political scandal since the 1976 downfall of the Gang of Four at the end of the Cultural Revolution.
Foreign media were not allowed to attend the trial and Mr Bo's remarks were carried on the court's official microblog, so are likely to have been highly edited.
"Regarding the matter of Tang Xiaolin giving me money three times, I once admitted it against my will during the Central Discipline Inspection Commission's investigation against me," Mr Bo said, referring to the party's top anti-corruption body.
"(I'm) willing to bear the legal responsibilities, but at that time I did not know the circumstances of these matters: my mind was a blank."
Mr Bo was charged with receiving about 21.8 million yuan (€2.6m) in bribes from Xu Ming, an entrepreneur who is a close friend and is in custody, and Mr Tang, the general manager of Hong Kong-based export company Dalian International Development Ltd, the court said.
Mr Bo called Mr Tang "a mad dog" who wanted to "frame me out of consideration for his own interests".
"This evidence has little to do with my criminality," Mr Bo said. "I was just hoodwinked. I thought it was all official business."
Mr Bo received the bribes through his wife, Gu Kailai, and his son, Bo Guagua, the court said, citing the indictment.
It was the first time that authorities had named Mr Bo’s son in the case. Guagua is now in the US, studying for a law degree at Columbia University.
Bo Guagua was not immediately available for comment.
Mr Bo's trial will last for two days and the verdict is likely to be in early September, state broadcaster CCTV said.
Court spokesman Liu Yanjie said Mr Bo was "emotionally stable and physically healthy" during the trial.
Underscoring popular support for Mr Bo, a handful of supporters protested outside the courthouse for a second day to denounce what they said was politically motivated persecution.
Police, who had blocked off the courthouse, hustled them away.
The charge of abuse of power against Mr Bo relates to the murder case involving his wife, the court said.
Mr Bo was a rising star in China's leadership circles when his career was stopped short last year by the murder scandal involving Ms Gu, who was convicted for the November 2011 murder of British businessman Neil Heywood, a business partner and family friend.
Mr Bo's former police chief in Chongqing, Wang Lijun, has also been jailed for trying to cover up the case.
Mr Bo could face a death sentence for his charges, though a suspended death sentence is more likely, which effectively means life imprisonment, or a 20-year term.
His guilt is believed to be an almost foregone conclusion given that prosecutors and courts come under Communist Party control.