With Toro Rosso running an all-rookie line-up, the majority of the focus has been on Sainz’s 17-year-old team-mate Max Verstappen. However, Button says he has spent time with Sainz - who openly talks about his admiration of Fernando Alonso - and is impressed with how the Spaniard’s approach to his first season in the sport.
“Everyone obviously talks about Verstappen and he is very quick, but when I sit down with his team-mate, Carlos, I think that he’s a very intelligent and I feel that he doesn’t just have the speed, he has other qualities as well,” Button said.
“He’s an intelligent guy and that can really make the difference in this sport. So I’m impressed by how mature Carlos is and I think that will show this season. When they have difficult situations I think his strengths will come through.”
In terms of how well Sainz is driving, Button says it’s tough to know how well either driver is performing at Toro Rosso as they are both rookies.
“There are so many young drivers. [Daniil] Kvyat is still young and he’s driving a Red Bull. So I think he’s found the step up a little bit more difficult than he probably imagined going up alongside Daniel [Ricciardo] in the A-team.
“The thing with the Toro Rosso drivers is they’re both young, they’re both doing a good job, but who knows how good the car is? There’s nothing to gauge the drivers against. If you had an experienced driver in the car you would know whether they’re doing a good job or not, now you don’t really know. So it’s tricky, I think we have to see at the end of the year really and look back on who we think was the strongest.”