Fernando Alonso revealed that he engaged in talks with Mercedes at the end of 2016 following Nico Rosberg's decision to retire from F1.
Mercedes was caught out by Rosberg's unexpected announcement to call it a day on his career in motorsport after winning the 2016 world title with the Silver Arrows squad.
Ultimately, Mercedes poached Valtteri Bottas from Williams but it also apparently sounded out Alonso.
"I've had contact with Mercedes in the past," the Spaniard told Man in Town magazine.
"Back in 2016, when Nico Rosberg decided to retire, I spoke with Toto Wolff. But we never reached a definite agreement."
The fact that no deal came to fruition between the two parties is hardly surprising given Alonso's likely air-tight contract with McLaren at the time.
Speaking about the future, the two-time world champion and double Le Mans winner reiterated his stance on a hypothetical return to F1.
"In the future, I'm open to interesting offers," said Alonso, who tested for McLaren earlier this year.
"If I decide to return to Formula 1, it'll only be if there's a real possibility of winning the world title.
"I'm not interested in projects that are starting from zero. I want a car immediately capable of winning.
"If Formula 1 becomes attractive again, I have no doubt that I would return."
At 37, Alonso is two years younger than F1's senior citizen Kimi Raikkonen and says age is currently not a factor as far as he's concerned.
"You feel that your body responds better between 25 and 30 years old, they're the years that I felt strongest physically," he said.
"But the experience that you acquire as time passes is also important."