Haas had looked strong in Friday practice but Romain Grosjean’s early crash in the final segment of qualifying, coupled with Kevin Magnussen’s misfortune – his first flying lap was hindered by his team mate's shunt before he was then held up by Ferrari's Kimi Raikkonen on his second attempt – meant Renault were once again the fourth best performer behind Mercedes, Ferrari and Red Bull.
Sainz had already continued his run of reaching Q3 at every Grand Prix this season (only Sebastian Vettel, Raikkonen, Lewis Hamilton and Daniel Ricciardo have also achieved that feat), and he was delighted to pull off a surprise result on Renault's home Grand Prix weekend.
“Yes, very happy,” he said. “Especially because we didn't expect to be best of the rest today. We were helped by the fact that Kevin had traffic with Kimi and Romain has had his accident.
“Haas this weekend are looking quite a bit stronger than us but we are there, P7, best of the rest once again so we somehow managed to pull it off.
“If the Haas cars come on the straight they might be very, very quick (on Sunday), that is the only concern. We look forward, try to get that clean air from P7, and hope for a strong race.”
While Sainz was clearly chuffed with his performance, his team mate Nico Hulkenberg was left slightly disappointed after failing to make it to the final shoot-out, and ultimately settling for P12.
“I was pretty happy with my lap, I lost a tenth on the exit of Turn 9 with some oversteer which you have sometimes on the limit," explained the German.
“It's been a little bit tricky this weekend. I haven't found the harmony and the confidence which I usually have so much in the car. That's why it was a little bit more difficult this weekend than when it's so close in the midfield.
“The Haas has been very quick this weekend. Yeah unfortunately in Q3 they tripped over themselves but not in Q2 when I needed them to but starting in 12th we can do something with the strategy, it gives us the flexibility at least so we'll see what we can do.”
Sainz will be hoping to bring his momentum into Sunday's race, with Renault currently leading McLaren in the battle for fourth place in the constructors’ standings.