Carlos Sainz Sr. has revealed that his son came close to making a switch to Renault.
The move was long rumoured, and is still thought to be on the cards by some, but the World Rally champion father of the Toro Rosso driver has now revealed it nearly did happen, only for Red Bull to apply the brakes.
"He was very close to leaving (Toro Rosso) because the offer was really interesting and he was interested, especially in the three years (contract)," Sainz Sr. said. "But in the end Red Bull did not let him go; they wanted one more year."
"The coming season can be a good year for Red Bull and they want to have someone (available) in case something happens, and they prefer that it is Carlos," he continued. "So on one side that is good and on the other side it is not."
Sainz Jr. is contracted to Red bull for 2017. The energy drink giants are keen for him to remain at Toro Rosso for at least another year.
Sainz's father continued: "Hopefully in the future he will take the step of going to a more competitive team and he can fight a little higher up.
"Next year should be the last year for Carlos at Toro Rosso," he said. "The normal thing is to move then to another team, because no one has been there (at Toro Rosso) for four years in a row.
"I think joining a team like Renault is an important step but hopefully in the future something like that will happen," said Sainz snr.
He also indicated that his son is likely to leave Red Bull to further his chances of being successful in Formula One.
"Red Bull (Racing) has young drivers confirmed for the next three years and so the future there is a little difficult," he said. "Unless one of them is upset and leaves, it will be difficult to make the jump to Red Bull."