Mercedes' non-executive chairman Niki Lauda believes Red Bull have fallen for Max Verstappen's negotiation tactics and paid too much to retain him.
In the second half of the 2017 season, Verstappen signed a new contract with Red Bull which will run all the way to the end of the 2020 campaign.
But, prior to the announcement, both the Dutchman and his father, Jos, both put pressure on the team by saying that they needed to supply a car capable of winning the World Championship in order for him to stay.
Verstappen was also rumoured with a move to Mercedes and, while that particular link was not quashed at the time, Lauda has said that no talks took place with the Silver Arrows.
Figures between $25m and $35m have been reported for how much Verstappen now earns a year, and Lauda feels he's been able to use Mercedes as a bargaining tool.
"We never made a proposal to Max." Lauda told Servus TV.
"I have a good relationship with Helmut Marko as we often talk and fly together. Today we talked about Verstappen and I told him that they could have saved a lot of money, since we never entered negotiations with him.
Marko, meanwhile, has defended Verstappen's new deal.
"We shared with him our plans for the future, guaranteeing that by 2020 we will have the best people and good options for the engine," he said.
"We went to the Honda base in Sakura and the infrastructure is incredible. This convinced him.
"He took advantage of the situation to get a raise in his money, but on this matter he is far from Vettel and Hamilton.
"If he can win titles he will approach them, but we have good prize money on top of a low base salary.
Red Bull still have to resolve who will partner Verstappen from the start of the 2019 season, with Daniel Ricciardo in no rush to commit his future to the team.