Alex Albon looks set to keep his race seat at Red Bull Racing for 2020.
When asked to assess Albon's first four races as a Red Bull Racing driver, Marko told Servus TV: "So far, all of his races have been very good.
"What he has done so far is a good recommendation for the coming season."
Marko has said he will make the decision about Verstappen's teammate for 2020 after the Mexican GP late this month.
"The only solution for us is to have two strong drivers in 2020 in order to compete for the constructors' championship," he said.
He said Albon still has some improving to do.
"His practice in Sochi was not so good. He crashed in qualifying. Alex won in Formula 2 the year earlier which may have made him excessively confident.
"He had to catch up in the race, but he solved this problem very well," said Marko.body check tags ::