Motorsports boss Bernie Ecclestone has denied making corrupt payments to a German banker to facilitate the sale of Formula 1.
But the F1 chief told the High Court he paid £10m to Gerhard Gribkowsky because he had threatened to "shake him down" over his family's tax affairs.
Mr Ecclestone denies making a "corrupt agreement" with Gribkowsky to sell F1 to a firm of his choice.
Media group Constantin Medien says it lost out because of the alleged deal.
But Mr Ecclestone says the German company's claim "lacks any merit" and he denies any "conspiracy".
In response to allegations that he made payments to Gribkowsky totalling £27m, Mr Ecclestone said: "It was £10m as it happens."
He told the court: "I made the payment... because he said he would shake me down concerning tax arrangements with our family trust... which would have been very expensive."
Constantin claims Gribkowsky "assisted" Mr Ecclestone to facilitate the sale of an important stake in Formula 1 Group by his bank - BayernLB - to a "purchaser chosen by Mr Ecclestone" - the private equity group CVC Capital Partners.
It says payments totalling about £27m were made to Gribkowsky, a senior executive at the bank, at Mr Ecclestone's instigation.
Philip Marshall QC, representing Constantin, said at a previous hearing that the deal allowed Mr Ecclestone to retain a position with Formula 1.
There had been a "real risk" of Mr Ecclestone's removal from his position in the Formula 1 Group, he added.
Mr Marshall said Mr Ecclestone had thought CVC would support his "continuing role as chief executive" of operating companies in the Formula 1 Group.
However, Mr Marshall said Constantin had investment rights in the Formula 1 Group and had been entitled to proceeds of any sale.
He said the bank's investment was sold "without the normal and proper process", which meant Constantin lost out.
Gribkowsky was given a jail term of more than eight years after being convicted of corruption at a trial in Munich last year, Mr Marshall added.
Constantin is seeking about £90m in damages.
Lawyers for Mr Ecclestone have previously outlined their case to the judge in written arguments, in which they said Constantin's claim "lacks any merit" and denied any "conspiracy".
Robert Miles QC said: "The claim fails on each of its elements: there was no conspiracy, there was no intent to injure Constantin... Constantin has suffered no loss."
Mr Miles said it had been arranged in 2006 that Gribkowsky would be given a "consultancy package".
He said: "Mr Ecclestone agreed to a pay-off because of the tax threats and insinuations which he had received from Dr Gribkowsky."
"It is true," Mr Ecclestone told the judge in court on Wednesday. "That's what I have always said."
He also refuted that he had said different things to journalists or changed his story.
"Most of these journalists, as you know, really should be closely working with Jeffrey Archer," he added.
The trial is expected to last several weeks.