Fleming had a reputation for being "incorruptible", said Mr Pownall, and the former captain accused Vincent of match-fixing.
Vincent recalled: "He said, 'I know you're dirty, I know Chris is dirty'. It was quite harrowing for a respected figure to corner you in a bar. It didn't make me feel good. I just wanted to run and hide."
Mr Pownall also questioned whether Vincent continued to fix matches after Cairns was suspended from the Indian Cricket League (ICL) in October 2008.
Vincent's scores in October and November that year were just 14, 0, 33 and 1.
"Did you fix any matches in those games or not?" the Queen's Counsel asked.
"I clearly don't remember," Vincent replied.
After Cairns was suspended from the Indian league, Mr Pownall said, there were rumours floating around the Chandigarh Lions in regards to match-fixing and corruption.
Vincent said he worried about the rumours and confirmed he was still in contact with Varun Gandhi, the Indian match-fixer who first approached him with money and a prostitute.
A number of players from the Chandigarh Lions were spoken to by ICL investigator Howard Beer, and Mr Pownall suggested that Vincent was "supportive" of Cairns following his departure.
"At that point of time, I was mates with Cairns, so of course," said Vincent.
The ICL then folded and Vincent was $US750,000 ($1.15 million) out of pocket, said Mr Pownall.
"It was extremely frustrating and disappointing," said Vincent, who had a three-year contract worth $US350,000 a year.
The ICL was quickly replaced by the Indian Premier League, another T20 tournament. This one was officially sanctioned by the International Cricket Council, which was run by Lalit Modi.
Mr Modi was described by Mr Pownall as an "extremely powerful and wealthy" businessman.
Cairns started libel proceedings against Mr Modi in 2010 for posting a tweet stating that Cairns fixed matches.
Last night, Mr Pownall produced an email chain that showed Vincent contacted Mr Modi in 2010 to ask about the libel case.
Vincent asked whether Modi was "going head-to-head" with Cairns and whether he had a strong case.
He also offered to meet him for coffee, but Vincent said the meeting never took place.
Vincent said he had been "disgusted at reading the lies from Chris Cairns" during the libel case, but Mr Pownall asked why he did not give evidence on behalf of Mr Modi.
"Here was a chance to do something to help and you did nothing?"
Vincent said his allegiance was to Chris Cairns and he was worried he would not be paid for his match-fixing.
Cairns then asked Vincent to give a statement on his behalf in the libel case.
Asked Mr Pownall: "Did you think Chris Cairns was completely mad to ask you to give evidence?"
Vincent replied: "Ah no, because I was working for him and he needed me to help him."
Mr Pownall responded: "The reason why he asked was because there was no corrupt activity between the two of you and you could give a truthful account."
Cairns is on trial on charges of perjury and perverting the course of justice arising from his statements in the libel case that he never cheated at cricket.
- Jared Savage in London