Max Verstappen and Carlos Sainz are rivals fighting for podiums at the front of the pack this season. At Toro Rosso, they were still teammates from 2015 to 2016. Red Bull Racing advisor Helmut Marko now reveals that the atmosphere between the two men proved very "toxic" during this period.

Sainz made his Formula One debut with the Toro Rosso team in 2015. Notably, as a teammate of Verstappen, who also made his debut in the premier class. The Dutchman was appointed as Daniil Kvyat's replacement at big Red Bull Racing in 2016 and became Daniel Ricciardo's teammate.

That left no room for Sainz to be promoted. With four races to go, Sainz eventually switched from the Toro Rosso team to Renault by the end of 2018. He then left for McLaren for two seasons before switching to Ferrari in 2021.

Marko took a big risk by putting two rookies in a team. Both men also had to prove themselves because their fathers were also drivers.

"He was unlucky to have Max as a teammate," Marko told the Red Bulletin. "The atmosphere between those two at Toro Rosso was quite toxic," the Austrian revealed. With the line-up we had at the time, I didn't see how we could keep him with us. So he switched to Renault, McLaren and then Ferrari."

However, Marko also admits that Sainz not only struggled at Toro Rosso because of his teammate, but that his father also played an important role. Carlos Sainz Sr. is highly regarded in motorsport and is considered a great legend.

"He has long been in the shadow of his father, the two-time rally champion. He has been unfairly saddled with the image of the spoiled son of a driver, while Carlos has always had to fight hard to get ahead," Marko concluded.