Reigning GP2 champion Pierre Gasly, 21, made his grand prix debut with Toro Rosso in Malaysia, replacing Daniil Kvyat.

The Frenchman will retain the seat in Japan this weekend and is expected to drive for the team in 2018 as well.

Marko has given a clear hint that confirmation of Gasly's 2018 seat at Toro Rosso is imminent and he made it clear that the company remains committed to promoting young drivers, while also taking a dig at his main rivals.

"I can tell you that pretty soon," Marko told Motorsport.com when asked about Gasly's prospects. "Red Bull, in complete contrast to Ferrari and Mercedes, have balls, and we put young drivers in the car. So let's see.

"We have our ideas, and as soon as everything is finalised we will let you know."

Marko said that the Frenchman had done the job asked of him on his debut in Malaysia.

"Especially in the first practice in the wet he showed that he's not scared, that he has good car control. Over the weekend there was no mistake, it was a very good debut from him," he said.

Asked about the prospects of Daniil Kvyat remaining with the team in 2018 he said: "As soon as we know we'll let you know."

Kvyat remains the only obvious candidate from the Red Bull talent pool, although former STR driver Sebastian Buemi – who has remained Red Bull Racing's third driver and has done a lot of Pirelli tyre testing for the team – could be an outside bet for what will be a development year for the squad.

Some paddock sources have suggested that Toro Rosso may look outside for 2018, citing Sean Gelael's Friday driver role as evidence that the team might need to take a driver with backing, with those potentially available including Pascal Wehrlein, Marcus Ericsson and Jolyon Palmer.

However Marko played down any such scenario: "We are Red Bull, we are different. It's difficult to imagine."

He also discounted the chances of F2 racer and Honda protege Nobuharu Matsushita, who doesn't yet have a superlicence: "I don't think he's ready yet."