Sebastian Vettel says he is not yet ready to retire.
"It's a very uncomfortable situation for him," Ferrari tester Marc Gene told AS newspaper.
"It's like when Alonso met Hamilton or Seb met Ricciardo."
But although a decade younger than Leclerc, 32-year-old Vettel insisted that he doesn't feel like a soon-to-be discontinued model.
"No, certainly not," the German told DPA news agency.
"I think age is not as crucial to us as it is in some other sports. But in the end, it's the same with every sport - if you're good enough, you're still young enough."
However, Mick Schumacher recently said that Vettel is now his mentor - just as Mick's father Michael was once a mentor to Vettel.
"Of course I know that already and it's nice to hear from Mick," Vettel said.
"I have been in Formula 1 for twelve years now and therefore I have a very different perspective than before. I judge things with a little more distance and not so quickly.
"It's the luxury of having a few years on the clock."
That said, Vettel insists that he is not yet thinking about retirement, even though his Ferrari contract runs out at the end of 2020.
"I do not intend to retire in the foreseeable future," he said ahead of the 2019 season finale. "I enjoy racing a lot.
"But I think it's normal that, twelve years later, I sometimes try to look ahead and think about what comes next. I don't think it's a good idea to just stop something that was so life-defining without an idea of how to go on."
Vettel said the ideal time to end his F1 career will be when it is still on his own terms.
"You should feel comfortable with the decision and be able to say 'Enough'. It's not ideal when the time is dictated from the outside," he said.
"For me it is clear - once I stop, then I stop and will not come back. You have to be happy and be able to say 'That's it'."