Cyril Abiteboul has urged Red Bull to think long and hard before jumping ship to Honda, claiming that the Austrian team will not win a title with Japanese manufacturer.
With the Austrian team continually delaying a decision on which engine it will use from 2019, crunch-time is fast approaching, with Helmut Marko claiming an announcement will be made by the end of the month at the team's home race.
"I understand what they are looking to get," he told Sky Sports. "They are looking to the technical and commercial side, because it is clearly different remaining a customer and partner of Renault versus becoming a works team with Honda. It is very different and I appreciate that.
"But frankly, as far as I am concerned, they have a chance with us to become world champion again," he added. "I cannot say that for Honda.
"With what they have now, what is coming in the pipeline, and their car which is clearly a great car, maybe the greatest out there, they have the chance to be world champion again within the next two years," he claimed.
"It is a complex decision for them and for us," he admitted. "Maybe it is my emotional side... I have been working twelve years of pulling my hair with Christian and Helmut, and I don't want to lose any of that.
"But frankly, in the construction of the Renault team, I think it is still interesting to get their benchmarking capacity. We know where we need to work based on what they are doing. They have showed that a Renault engine can win races in straight conditions, so that is a good sign of what we are doing, where we are progressing and where we need to progress."