In an interview with Spain's AS newspaper the pair was asked who the most talented driver on the grid is, and who they think the favourite to win the championship is. The pair's answers were unanimous.
On the best driver, Verstappen said : "Alonso."
Sainza agreed, adding: "Fernando, of course."
They believe Alonso is the best driver, but think Mercedes driver Lewis Hamilton will defend his title this season.
When asked about the title race Verstappen, who is only 17-years-old, said: "Hamilton. The car he has is amazing."
Verstappen also responded to those who were critical of his signing because he is so young, saying: "When you are offered the chance to drive in F1, no matter your age, you must accept it. It could be a long time before you get another."
Sainz, who is 20-years-old, was hesitant to say where he hopes to finish at the end of the 2015 season.
He said: "It is impossible to set goals without having even tested the car.
"But I think both Toro Rosso and I want to be in the points and hopefully we can be fighting for the top ten, but the truth is that I don't know where we will be."