Red Bull denies double-DRS is the key to its turnaround in form

Sebastian Vettel put himself firmly back in the hunt for the world championship with victories in Singapore and Japan - as it emerged in Suzuka that the team has followed Mercedes' lead and raced a double-DRS.

Unlike the Mercedes version that channels air through a duct to stall the front wing, it is understood that the Red Bull version flows the air to the beam wing to help stall that and the diffuser.

Its effectiveness has been highlighted by a big step forward in its qualifying pace in the last two races - but Red Bull team principal Christian Horner thinks the double-DRS is not the only factor that has helped the team start winning again.

"As with all these things there is never a silver bullet, and I think it would be very difficult to say that the car's performance here is down to a rear wing," he said after seeing Vettel cut Fernando Alonso's championship lead to just four points.

"I think we have made progress in all areas and it is about chipping away at the detail.

"We had the fastest pitstop in Japan for example, so it would be wrong to say our upturn in performance is about finding a few kilometres on the straight."

Although the existence of the Red Bull double-DRS only came to light in Japan, Horner says the team had raced it before - and it was likely to have been run in Friday practice sessions too.

Horner thinks that the team's ultra strong performance in Japan - where it was in a class of its own - was down to a combination of factors.

"I think the car has worked well here in all conditions, low fuel, high fuel, and on long runs on the two compounds of tyre that we have been presented this weekend. I think the nature of this circuit suits the car.

"But we have seen how performance moves around, so there is absolutely no predictions that we can take out of this event, other than we need to keep pushing, we need to keep bringing performance to the car and the championship now is effectively a battle of five races between Fernando and Seb.

"You can't rule out the others, but whoever does the best job over the next five races will ultimately prevail."