Carlos Sainz has admitted that he is "angry" but also "patient", as his career stalls for now at Toro Rosso.
The Spaniard had a very good 2016 season, but it was his Toro Rosso teammate Max Verstappen who got the call to move into the senior team.
Not just that, Sainz got an offer to switch to the Renault works team for 2017, and was also linked with Nico Rosberg's Mercedes seat.
However, Red Bull would not let him go.
"It's difficult," the 22-year-old told Spain's El Pais.
"Doing a year in Formula 1 like the one I did is very difficult. That's why I'm angry that I am not moving forward. We had a very interesting offer from Renault that in the end was rejected by me as much as it was by Red Bull.
"That's life. If I had done that season in any other year I think I would have got a seat at Red Bull, but now the team is full, they are very happy with the two drivers they have. As I said, that's life, and sometimes Formula 1 is difficult to understand. I just have to have patience and it will come."
Sainz finished 2016 in 12th place with 46 points.
