Daniel Ricciardo going on the market for 2019 is "understandable".
That is the view of Dr Helmut Marko, the Red Bull official who admits the energy drink company is having to look beyond Australian Ricciardo’s current contract.
"For all his racing life Ricciardo was part of the Red Bull family," he told Kronen Zeitung newspaper.
"That he wants to look at other things now is understandable.
"A decision will be made in the first six races of 2018," Marko added. "Max (Verstappen) has a contract for another year (2019)."
After Verstappen’s Sepang win, Marko said Red Bull is happy with its form in the second half of this season.
"For the first time in this terrible hybrid era, we overtook Mercedes on the road and beat them," he said.
"This is a huge satisfaction because everyone knows we have less horse power," added Marko. "This shows that our chassis development was sensational."