Renault F1 interest validates my form, Toro Rosso's Sainz believes

The Spaniard agreed a new deal to stay at Toro Rosso for 2017 with Red Bull, to which he is contracted, then had to turn down interest from Renault later in the year.

Sainz has insisted he wants to fight for the title with Red Bull, but that is not currently a possibility with Max Verstappen and Daniel Ricciardo contracted to its lead team until the end of 2018.

The 22-year-old, who has emerged as an outsider to join Mercedes as a replacement for the retiring Nico Rosberg, is staying upbeat about his future.

"When you get such an interesting and good offer from a future top team, like Renault, it's not easy to take that decision," Sainz told Autosport.

"But in the end, together with Red Bull and after some conversations we came to a conclusion that the best for me was to do an extra year at Toro Rosso.

"After not signing an interesting offer at a top team, this gives me the tranquillity.

"If I keep performing in this way and improving, I'm sure opportunities will open up and I will try my best for this to happen, and to make my way into a top team.

"For now, I'm happy and hopefully I've taken the right decision to go with them."

Sainz conceded he found it hard to see how he would earn promotion to Red Bull before 2019, but he remained hopeful.

"When you listen to how happy Red Bull is with its drivers, it is very tough for me to think that they're thinking about me," said Sainz.

"But maybe next year everything changes, one of them is upset, or doesn't perform and suddenly an opportunity opens up for me at Red Bull.

"At the moment I see them so happy and it is very tough for me to see that they trust me for a seat next year in 2018.

"So that's why I need a strong 2017 to open all the possible doors in Formula 1."