Signing up Esteban Ocon to be Lewis Hamilton's Mercedes teammate in 2020 was ruled out by Toto Wolff because of the "risk".
Instead, the Wolff-promoted Ocon is emerging from his sabbatical with Renault this year, while Valtteri Bottas keeps his seat alongside Hamilton for another season.
"Putting him against Hamilton, who has been with Mercedes for seven years and is at the peak of his career, is not good for him, especially after a year off," Mercedes boss Wolff is quoted by Speed Week.
"It may have been an exciting story and he probably he would have done well, but there is only one guy who did well against a superstar and that was Lewis Hamilton," he added, referring to Fernando Alonso in 2007.
Wolff continued: "Drivers need time, and I don't want to risk his career or that he risks doing anything to win against Lewis. That was the critical point."
Indeed, Wolff was particularly nervous about disrupting the harmonious Hamilton-Bottas partnership in favour of another potential Nico Rosberg-style clash with Ocon.
"When managing drivers, you have to be aware of the fact that they are realising their dreams and their main goal is to win the title," he said.
"This can lead to tensions because these goals do not always match the team's goals.
"But I'm really proud that over the years we've always managed to get the drivers behind Mercedes' goal of becoming one of the world's most successful sports teams."
