Red Bull to keep tabs on Toro Rosso's Honda performances

Red Bull team principal Christian Horner will monitor Toro Rosso's progress with "great interest" in 2018 as the four-time champions ponder which engine supplier to choose for the 2019 season. Red Bull's relationship with Renault has grown strained in recent years as they have struggled to keep pace with Mercedes.

The hybrid era has seen the Silver Arrows replace Red Bull as the sport's dominant team.

Though Max Verstappen and Daniel Ricciardo are evidently drivers capable of race wins, and likely championships, Red Bull have often been left chasing Mercedes.

It appears as through the gap has narrowed at the start of 2018, but Red Bull regardless could opt for a new supplier when their Renault deal expires at the end of the year.

Sister team Toro Rosso stole the spotlight in pre-season, with shows of great reliability from a Honda unit which had previously infuriated McLaren and Horner's interest has already been caught.

"Honda has had a fantastic start with Toro Rosso," Horner told El Confidencial.

"Obviously, we're in a good position to keep an eye on their progress in the first half of the year.

"We're going to follow it with great interest."

Renault managing director Cyril Abiteboul has previously suggested Red Bull will have to make a decision by May, but Horner does not want to be held to deadlines.

"What we understand is that May is when you have to give an indication to the FIA, but that does not mean a commitment," he said.

"It will be decided at the end of the summer. That's the realistic timing of when the decisions have to be made."

Abiteboul has also suggested that Renault's customers are not likely to be able to stick to F1's three-engine limit in 2018.

"We will have to see how it goes this year, but whenever we have a power deficit, we have to try to compensate with the car," Horner added.

"It will be interesting to see who uses only three, but even if the regulations were more lax, the order of performance would not change.

"The problem is that this generation of engine regulations is not as good for Renault as it has been for Mercedes and Ferrari."