Verstappen complained about his engine's power delivery on team radio on Friday and again in FP3.

The team estimated it would be on the third row of the grid in qualifying, but Verstappen earned second place, despite having to abort his second and faster run due to an engine cut-out. His team-mate Daniel Ricciardo was sixth.

Formula 1 Motor racing-Alonso ready to help Renault at race weekends this year 4 HOURS AGO

Horner was careful not to direct any blame at Renault, noting that the Spec C power unit - which only Red Bull is using - is still early in its development curve.

Although Verstappen suggested that it would be less of an issue in race trim, Horner says that Renault will do some more work at its Viry base.

"It's probably a numbers issue, which you're allowed to change," said Horner.

"Under normal circumstances you'd expect some simulation or dyno time going into hopefully tidying that up.

"The Renault guys are working flat out on it.

"This is the Spec C, it's still new.

"It's delivered the power, so it was definitely the right call to take the engine into this qualifying.

"Despite the issues it still has a bit more power.

"We just have to tidy it up for the race tomorrow.

"Hopefully it will be cleaner than when he drove out of the pits today."

Horner explained that Verstappen had to adjust his driving to deal with the issue with the power unit, which allowed him to join Lewis Hamilton on the front row of the grid.

"Unfortunately with the mapping he's just not getting the delivery of the power than he's requesting from the pedal, so it's very intermittent," he added.

"That's what's been having him over in terms of downshifts and on upshifts.

"It was a fantastic lap, and unbelievable effort.

"To drive round the issues he had was truly impressive.

"It was a shame, I think without it we could have had a shot at the pole there, but to be starting on the front row feels like a pole position anyway.

"I think going into qualifying the engineers thought fifth and sixth was the likely outcome, so I think they've done a good job in getting the chassis tidied up."

Formula 1 Motor racing-Former McLaren boss Whitmarsh joins Hamilton's commission 5 HOURS AGO