Pierre Gasly has Red Bull's full support, but he must perform if he wants to keep his race seat at the senior F1 team.
That is the warning of Dr Helmut Marko, who runs Red Bull's notoriously tough driver programme.
Max Verstappen is quoted by Speed Week: "When it became clear that Daniel Ricciardo was going to Renault, it was obvious that Pierre would come.
"He is a great guy. I've known him from karting. He is straightforward, smart, nice -- you cannot ask for more," the Dutchman said of his new teammate.
Red Bull team boss Christian Horner has said that Gasly, who steps up from the junior team Toro Rosso, will get some time to get up to speed in 2019.
But Marko said: "Pierre Gasly will be under scrutiny, because that's the way formula one is.
"It's the same in football. If you don't perform, you go to the bench.
"Gasly has proved he is fast, now we have to teach him a little more discipline," Marko added. "But he gets a lot of support from the team, and we're sure he'll make it."
