Mercedes driver Lewis Hamilton may have claimed pole position for the United States Grand Prix but he will need to be at his best to defend from Kimi Raikkonen and potentially also Sebastian Vettel.
That is the concern of Mercedes team principal Toto Wolff.
The Brit starts at the front of the grid after finishing 0.061 seconds faster than Vettel – who will start in fifth due to a penalty – with Raikkonen in second ahead of Hamilton’s Mercedes team-mate Valtteri Bottas.
The Finn will start on the quicker and grippier ultra-soft tyres, compared to the super-softs of Hamilton, Bottas and Vettel in what will undoubtedly pose a huge threat to Hamilton’s hopes of winning a fifth successive Grand Prix in Austin.
Ferrari’s Vettel must finish second if Hamilton does pass the chequered flag first, or else the 2018 championship will go his rival’s way.
Hamilton only needs to outscore the German by eight points to decide their battle although Ferrari have shown strong form while Stateside having been well below in the last three rounds.
And Wolff is concerned that the Ferrari pair’s pace down the straights will be dangerous, with even Vettel himself admitting he was shocked by how “surprisingly close” the Prancing Horse were with Mercedes in qualifying.
Wolff said: “It’s so close between the top three. I’m happy today, but my thinking today always goes to tomorrow.
“We’re lacking a bit of straight-line speed, and it’s going to be very difficult to defend against the Ferraris attacking us – that’s my worry.
“I’ve always said you cannot write them off. You guys have been saying they have imploded, it doesn’t go like this.
“It has always been very close all season between Ferrari and Mercedes – and it is going to continue until the end of the season.
“It’s about getting the best possible race result and if it doesn’t happen tomorrow for us, then we will try again in Mexico and try and get one step closer.”
Hamilton, meanwhile, welcomed the competition as he insisted that he would relish more consistently-thrilling qualifying sessions like that of yesterday’s.
“They were obviously very quick,” Hamilton told Sky Sports F1 after qualifying.
“This weekend, we’re pretty much on a par performance-wise.
“As Seb [Vettel] said, they’ve gone back on some of their potential updates and the car is better in the sweet spot and for us, we’ve not brought updates here so we’re on max downforce level here.
“That’s great to see us so close and still I’m hopeful for the future to have more teams, more qualifying sessions like that, that are closer, but with more cars involved.
“That’s got to be the ultimate goal for Formula One.”