New Renault F1 engine could swing Red Bull/Ferrari battle - Horner

Renault's updated power unit made its debut in this week's Barcelona F1 test.

The outing was considered successful enough for Renault to bring its first race forward from the original plan of the Canadian GP next month to Monaco next weekend.

Red Bull, which has retained Renault engines under TAG Heuer branding this season, ended a 20-month victory drought with Max Verstappen's triumph in Spain last weekend.

Horner praised Renault for its progress and is optimistic about what is coming next.

"I have to play compliment to our TAG Heuer engine partners who have done a great job in making progress," he said.

"With what is in the pipeline for coming races, there is a lot of reason for optimism.

"If we get what is advertised and it's going to put us in a position to at least race Ferraris every weekend then hopefully we can start to get into starting to close that gap down to Mercedes at certain circuits.

"Daniel [Ricciardo] qualified within 0.65 of a second of Lewis Hamilton [in Spain], which is the closest that I think anyone has really been in the last 12 months.

"At a track like Barcelona, that is really encouraging. If we can find a few tenths on the power unit side, it'll certainly be gratefully received."

Renault will only have enough parts to bring one of its new engines for each of its two teams in Monaco.

Red Bull will have to decide whether Ricciardo or Verstappen should race the new unit first.

Though Renault had always been confident the new engine would provide more power, its initial misgiving over a Monaco debut had been that its driveability might not be so refined at first.

Before Renault decided it would bring the engine to Monaco, Horner insisted there would be no extra pressure from Red Bull on that front.

"If there was any opportunity to be more competitive in Monaco of course we would take it but that is a decision for the guys from Renault," he said.