Daniel Ricciardo is facing a claim of more than £10m in alleged unpaid earnings from his former manager.
Glenn Beavis has filed a lawsuit in the High Court in London claiming that Ricciardo has not paid him commissions owed on his new contract with Renault.
Ricciardo left Red Bull at the end of last season to join the French team.
Ricciardo's lawyer, Jeremy Courtenay-Stamp of Ebury Partnership, said there was "no merit" in the claim and added: "We are going to defend it fully."
Legal documents lodged by Beavis' lawyer at the High Court and seen by BBC Sport make a claim for "in excess of £10m" for "various sums due in accordance with the commission agreed between the parties".
Ricciardo's salary and bonuses included within his two-year contract are listed in the court documents but have been redacted from those publicly available via the High Court website.
But the details of the claim suggest the 30-year-old Australian's Renault salary is more than £20m.
The first defendant is Whitedunes International Holdings Limited, a British Virgin Islands company wholly owned by Ricciardo, who is the second defendant.
Beavis' claim is that he had an agreement with Ricciardo that saw him earn "20% commission on the value of all new deals (he) introduced and which were subsequently concluded".
He claims he started negotiations on Ricciardo's behalf with Renault Sport managing director Cyril Abiteboul in mid-2017, which continued into 2018 before heads of agreement were agreed on 2 August 2018.
Beavis' lawsuit says Ricciardo told him on 15 December 2018 that he wanted to terminate their agreement but it was agreed that Beavis continue because "there were various outstanding matters to be dealt with first, including negotiating the long form of the Renault driver contracts".
Beavis' claim says he continued working with Ricciardo, with Whitedunes' permission, until 31 March and that the long-form contract was concluded on 7 March, a week before the first race of this season.
"The position of the defendants… is that the claimant has no entitlement to the commission or to any other form or amount of commission in relation to the Renault contract," reads the lawsuit.
Ricciardo's lawyer has not yet filed his defence and says he has until the end of July to do so.
Courtenay-Stamp said: "I can confirm that Ebury Partnership and I act for Daniel Ricciardo in relation to this claim and Daniel's position is very clear - there is no merit whatsoever in relation to this claim and we are going to defend it absolutely fully.
"You'll have only seen his claim so far. You won't have seen our defence because it hasn't been filed. But it will be filed and it will entirely refute the claim that Beavis is making."
A spokesperson for Renault said: "This is a private matter between Daniel and a third party and therefore it is not our place to comment."