Max Verstappen never expected to adapt to the RB12 so quickly after qualifying fourth on Saturday, having never driven the car prior to this weekend's Spanish Grand Prix.
The Dutch driver was promoted from Toro Rosso to the sister team just last week, but was immediately on the pace, lapping quicker than team-mate Daniel Ricciardo in both Q1 and Q2, before falling just short in the final session.
"I enjoyed the qualifying, it was getting better with every lap," said Verstappen. "For me the target today was to enjoy myself and I had a good feeling in the car. I focused on what I had to do and it worked.
"I'm happy, I didn’t expect to adapt to the car so quickly. I didn’t expect to be on the second row, so it’s a positive feeling. We are close to a podium and hopefully we can keep our positions in tomorrow’s race."
Ricciardo starts third as Red Bull emerged as Mercedes' nearest rival in Spain, and the Australian is hoping to finish on the podium for the first time this season.
"Firstly I’m really happy to be back in the top three on Saturday and will try and be back here tomorrow!
"I'm happy for both of us to be in front of the Ferraris, we are both on the second row, which is pretty awesome.
"It took a bit of time to come together, but in Q3 I knew I had one lap and knew I had the pace and where I could do it; it was about putting it all together – up until then I hadn’t, but Q3 is what counts and I did it, so I’m really happy."
Team principal Christian Horner described the duo's performance "amazing" after their best qualifying result for some time.
"An amazing performance by both of our drivers today," he added. "It was a phenomenal final lap by Daniel Ricciardo, he only had one set of tyres in Q3 but he made the most of them and nailed the best lap of the weekend to line up third.
"Max Vertsappen, making his debut for the team this weekend, has proved to be the sensation that we know he is. He will line up alongside Daniel on the second row, in front of the Ferraris, which puts us in a great position for tomorrow’s Grand Prix."
