Renault’s upgraded power unit delivered “exactly what was promised” according to Red Bull team boss Christian Horner, after Red Bull challenged Mercedes on ultimate pace in Monaco.

Although Red Bull and Renault came close to divorcing last season when a highly anticipated upgrade failed to deliver a step forward, casting doubts over whether or not the French manufacturer would ever catch up to rivals Ferrari and Mercedes, the two parties recently agreed to continue together until 2018.

That deal was finally signed off after a successful test of Renault’s latest spec power unit in Barcelona a fortnight ago, with Monaco offering further evidence that Renault has taken another step forward in catching its rivals.

“The upgraded power unit has delivered exactly what Renault said it would and that’s certainly a positive as we head towards more power-related circuits,” said Horner. “We’re relishing the prospect of the next few races.”

Whilst it offered a small gain in Monaco, it’s expected to offer up to half a second at power sensitive circuits such as Canada, giving Red Bull a chance to challenge Mercedes on a more regular basis.

“At Monte Carlo it gave us exactly what was promised, which was about 0.2s [a lap]. That certainly helped to achieve pole position, so hats off to everyone in Viry, they are doing a great job at the moment. The TAG Heuer power unit is performing better and better,” he added.

“A lot of restructuring and hard work has gone on at Viry over the last six to nine months and we’re just starting to see that the organisational changes there are starting to bear fruits, so it makes sense to extend a relationship that is working well for a further two seasons.”