Red Bull Racing will decide in the first half of 2018 whether to switch to Honda power for next season, says Helmut Marko.
The Milton Keynes-based outfit will monitor and assess the performance of junior bull squad Toro Rosso in the first part of the season.
Speaking to Auto, Motor und Sport, Marko says he has been "positively surprised" by what he has seen from the Japanese manufacturer so far despite the dismal underperformance it showed with McLaren in the past three years.
"So far we're positively surprised by Honda, also in terms of their dedication and enthusiasm," said the Red Bull motorsport boss.
"I think they have learned from the mistakes that certainly happened.
"So far, according to the test stands, the engine is reliable. I think it will be possible for the engine to catch up to Renault level by mid season," Marko added.
And if that happens, Red Bull is likely to make the switch from Renault to Honda for 2019.
"The regulations have changed so that you have to announce what engine you want to compete with the following year by the summer," said Marko.
"We will analyse thoroughly and then make a decision."
Should Honda once again fall short of expectations however, it's unclear what options Red Bull would rely on given that current partner Renault has allegedly already decided not to extend its engine supply deal with the team.