Daniil Kvyat has revealed he had a series of “heated moments” with Carlos Sainz during their time together in the Red Bull junior programme.
Both Kvyat and Sainz were promoted to Formula 1 in 2014 and 2015 respectively having spent a handful of years under Red Bull's racing umbrella.
The pair competed against each other in various junior formulae, with Sainz beating Kvyat to the Formula Renault 2.0 NEC title in 2011.
As they vied for supremacy in the Red Bull set-up, Kvyat told Formula1.com that matters between the duo became heated at times.
“Today me and Carlos are really good friends, but when we were teammates there were some heated moments,” said Kvyat.
“We travelled a lot together, we had some contact on the track, and sometimes even our fathers had to intervene and say, ‘Hey, guys, calm down!’”
The 2013 GP3 Series was Kvyat's last year in racing before he was handed a seat in F1 with Toro Rosso, as Dr Helmut Marko issued the two former rivals with an ultimatum.
“During the GP3 season, Helmut told us, ‘OK, an F1 seat is on the table, so whoever does best will probably get it’, and that’s when it started to be very serious,” Kvyat said.
“I remember the round in Belgium, where we started first and second, almost tied on points, and I had to get that win. I won it, Carlos had a crash and I got a big lead in the points.”
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While Kvyat was on his way to the GP3 Series title, he also competed in the FIA Formula 3 European Championship.
As he impressed in a new car while Sainz struggled to get up to speed in Formula Renault alongside his GP3 venture, the pendulum swung in Kvyat's favour for a 2014 seat.
“There was another European F3 championship at the time, with a bit of a different car,” Kvyat reflected.
“Helmut wanted me to also do some races in that series, to do well in both cars, and I started winning there as well.
“I remember a race at the Red Bull Ring and it was close to Helmut, so he came to say hi, and I did three pole positions out of three, so that was a very important step.
“Then Carlos felt it and he said he’d do the World Series by Renault, just to show Helmut that he could do well in both cars, only that in his case it wasn’t going as well.
“So, more things were in my favour, I won the GP3 title and I was offered the Toro Rosso contract for 2014 before the last race.
“It felt like a huge achievement at the time, putting my signature on it.”