Having faced the prospect towards the end of 2014 of there being no room at all for him in the Red Bull F1 programme, the sudden opening up of a Toro Rosso seat for last year had the downside of him going up against the hype and brilliance of Max Verstappen.

His speed against the Dutchman was well acknowledged, which is why it hurt so much when it was Verstappen who got the nod to replace Daniil Kvyat mid-season.

Having picked himself up from that, he faced added frustration when a potential sensational podium finish in Monaco was stolen from his grasp thanks to a botched pit stop.

But Sainz is not a man to dwell on lost opportunities or moan about his lot: he is an intelligent hard worker with a sensational amount of speed to boot.

And, having come through all the challenges thrown at him over the past few years, he thinks now is his time to show what he can really do as he targets a top-line seat for 2018.

"I do have that confidence," he told Motorsport.com in an exclusive interview about the self-belief that has come from overcoming everything that has been thrown at him.

"That confidence is something you need to have in F1. I've managed to have it always inside me.

"Sometimes you show it, sometimes you don't show it so much. I truly believe that I have it: and now it is my turn to show Red Bull and show Helmut Marko that I deserve a chance in a top team.

"You ask any driver and they will say the same - "I want a drive in a top team" - but I truly believe I can do it and I truly believe I can keep pushing for it."

Hard work

Sainz is well aware that a top line F1 seat he so craves is not going to fall into his lap, which is why he is ready to knuckle down and throw everything he can with Toro Rosso.

He admits it is hard balancing the impatience to get his hands on race-winning machinery with the need to do his best now in machinery that is not capable of delivering right at the front – but he knows there is only way to achieve his aim.

"It's not so easy. That is why I prefer to use words like 'I am going to try', 'I am going to push for it'," he explained. "The phrase 'I want to be', it doesn't matter what you want to be! You can try, you can do your best but the next thing you need is a tiny bit of coincidence that puts you in the right place in the right moment.

"It is like [Daniil] Kvyat maybe two years ago when he jumped from Toro Rosso [to Red Bull], and Max in Barcelona this year. That tiny bit of luck of being in the right place in the right moment to make the jump is important. And you need a lot more factors than just performing at a very high level, so we will see."

Sainz knows only too well how circumstance often favours the hard workers – for he readily acknowledges that the domino effect of Fernando Alonso's departure from Ferrari to McLaren at the end of 2014 triggered the opening of that Toro Rosso opportunity.

"You get well associated to coincidence and luck – but I prefer to think it is just hard work," he said. "I went through a very difficult year in 2013, where they chose Daniil Kvyat over me and they gave me an ultimatum of winning World Series [Formula Renault 3.5].

"I did a lot of changes into my driving preparation and finally came out like the driver you see today. In World Series I won the championship - but then there was the Max Verstappen news, and then it looked like they were renewing [Jean-Eric] Vergne for another year to share with Verstappen.

"But suddenly circumstances started to happen – and that was actually thanks to Alonso. Him leaving Ferrari, Vettel going to Ferrari, Kvyat going to Red Bull and me coming to Toro Rosso.

"Of course it is a point of coincidence, but I truly believe that without that title in World Series and that year performing to Helmut Marko was key."

Every Red Bull driver knows only too well the pressure cooker environment that Red Bull motorsport advisor Marko puts youngsters through.

And yes, for all the difficulties that delivering for Marko entails, Sainz is well aware of the positives that come from the Austrian's hard school of knocks – and the odd lecture about where he must improve.

"Totally!" he explained about the stress of delivering for Marko. "Especially when you are 15 years old, you arrive to a programme like Red Bull and you need to shake hands with Helmut Marko and tell him how grateful you are for being in a programme and promising you are going to perform.

"It is tough for a 15-year-old. You don't have the maturity to face a guy that is so imposing, so it is very tough. But that is what builds your character – from 15 years told to have meetings with him, even if he gives you a lot of criticism, to face him, to take it. And go year by year maturing and being able to win in every category and being able to perform.

"Then suddenly you arrive in F1. You are 19/20 years old and you feel you are like 30 because of the education you had to go through these five years. It has its pros and cons, but I found it more pros than cons."

Verstappen rivalry

What gives Sainz a lot of confidence that he can do the job is how well he did against Red Bull golden boy Verstappen.

For with even Daniel Ricciardo finding himself put under pressure by Verstappen's arrival at Red Bull, Sainz knows that the job he did against the Dutchman was pretty impressive.

"I think it is a very different situation because Daniel in the end had already had three wins, and everyone knows how good Daniel was," he said. "My situation was different because all that hype was surrounding one guy who had arrived to F1, and we were both starting from zero.

"It was much more difficult for me to survive that year and actually be able to perform at a decent level. It was already very tough and to create an impression, and to come out the second year and do another step was even tougher.

"So I think the circumstances that I arrived in F1, I am very lucky to get here. They were very far from ideal, so to still come on top and say 'look here I am, I am here to stay' it is definitely not easy."

And there is one other factor that Sainz thinks could make him even more formidable for 2017 – when he should get his hands on a decent power plant.

For he reckons the difficulties he has faced racing with under-powered engines over the past two years have made him so much stronger on track.

"Definitely," he added. "You cannot imagine that the amount of improvement I have made in that area since Australia 2015. Then it was easy to arrive and as a rookie put the excuse, 'I just don't have enough top speed to overtake, it is impossible, when I open the DRS I can only match their speed.'

"After nearly 40 races in F1, I found the way. I didn't know how to overtake people when we were 20km/h down, like we are in some places, so to find spaces where you never thought they would be, or you use the battery, plus DRS, and maybe a bit the tyre in that corner, it is incredible.

"I am grateful for it. I don't regret it all. I think it is just life wanted me to have two tough years in F1, but I am convinced it has made me better for the next years."

In 12 months time, will Sainz be one of the key players on the F1 driver market? You bet.