The 22-year-old drove terrifically last season in his rookie campaign for Sauber and many think the youngster can give the veteran a run for his money next season.
However, others believe a clear 'Number 1 policy' may be used in Vettel's favour.
"Leclerc looks really good and he has a great future ahead of him," Mario Andretti told Sky Italia. "It was always Sergio Marchionne's plan to take him to Ferrari.
"But I don't know if it's the right time for him. In every team there must be a first and second driver. Two number ones never works."
But Rivola, who knows Leclerc from the Ferrari Academy, believes the Monegasque driver can take on Vettel in 2019.
"I believe and hope that Ferrari will give both the same opportunities, and that the best will prevail," Rivola told La Gazzetta dello Sport. "There is no doubt that 2019 is considered an apprenticeship for Charles, but you can be sure that he will try to win right away."
Rivola added that he sees similarities between Leclerc and Formula 1 legend Fernando Alonso, who has just retired from the sport.
"I had the opportunity to work with Sebastian when he debuted in Toro Rosso, and with Alonso in his debut season in Minardi," Rivola continued. "It is Fernando with the same anger as Charles in qualifying, and the same ability to always show amazing results."