Red Bull says that Mercedes’ “surprising” engine power increase has left it confused as to how to keep its Formula One title rival from moving away.

Red Bull team boss Christian Horner believes the competitive picture between the two F1 title rivals has evolved in recent weeks, following Max Verstappen’s failure to match Valtteri Bottas’ performance in the Turkish Grand Prix.

Despite the fact that Red Bull appeared to have a speed advantage heading into the summer break, he believes that the debut of Mercedes’ new engine specification at Spa has enhanced the German car manufacturer’s straightline speed.

And, although Red Bull could previously counter any top-speed advantage from Mercedes by running a lower downforce configuration, Horner believes that the difference between the two teams is now too great for that to be possible.

Even though he was running a higher downforce rear wing, Lewis Hamilton was able to draft past Sergio Perez on the back straight in Turkey at one point during the race.

“Their straightline speed has taken a significant step recently, and I think that whereas we could match them with smaller wings previously, now we can’t get near,” said Horner when asked about where Mercedes’ current advantage came from.

“We saw that particularly at this circuit, where Lewis in particular had a significant straightline advantage with a bigger rear wing of the car.

“We’ve got to maximise our package as best we can. And, as I say, it’s surprising that they’ve made the step that they have with the power unit.”

Mercedes has been battling with engine reliability issues with its older power units, but the recent introduction of new components for Bottas and Hamilton has relieved some of their concerns.

The nature of the current long-life engines also means that they produce greater power when they’re new, with a gradual performance decline over time.

Mercedes’ advantage in Turkey bodes well for its chances in the following race, the United States Grand Prix, with high-altitude venues like Mexico and Brazil likely to favor Red Bull after that.

Horner believes the current situation is too close to call, and his team cannot afford to let any opportunities pass them by.

“We know the next race in Austin has been a Hamilton stronghold for quite a few years,” he said. “But then Mexico and Brazil, hopefully higher altitude races tended to be quite strong for us in the past. Then I’m really not sure what to expect from the last three.

“It’s going to be fascinating, but you know we are going to have to be at the very top of our game.

“We’ve managed to extract the maximum that we possibly could here [in Turkey], with great execution in the pit stops, and good strategy. So that was positive. But certainly this venue has been strong for Mercedes on outright pace.”

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