Pierre Gasly must demonstrate "more discipline" when driving for Red Bull in 2019.

Dr Helmut Marko, Red Bull's mercurial F1 driver manager, scolded the Frenchman for disrupting the team's pre-season development programme in testing.

"We brought things to the test that we could not fully develop due to the Gasly crash," he told Germany's motorsport-magazin.com.

Gasly, in just his second full season of F1 in 2019, has moved up from Toro Rosso to replace Daniel Ricciardo.

"Especially the second crash was completely unnecessary," Marko said of Gasly's incidents during the eight days of Barcelona testing.

"It threw our entire test programme overboard. He must clearly show more discipline," he added.

It means Red Bull is travelling to Australia for the season opener with question marks over the Melbourne specification.

"We could not test the parts in the complete package, but only in individual parts, so we are not sure," Marko said.

But Christian Horner, the Red Bull team boss, backed Gasly.

"His natural speed is obvious, there is no doubt about it," he told France's Auto Hebdo. "He just lacks a little experience."

But Horner said the difference between Toro Rosso and Red Bull will be "huge" for the 23-year-old.

"All of a sudden, you find yourself in the spotlight with his performance compared to Max Verstappen, one of the stars of F1 at the moment.

"It's a huge challenge for Pierre, but I'm sure he has the right mindset and he can count on the support of the team," Horner added.

"Pierre has probably been promoted 12 months earlier than expected but life is like that. Now he has a fantastic opportunity to leap at it.

"If he can be close to Max, score a lot of points and get on the podium, that would represent good progress compared to last year," he said.