Lewis Hamilton is expecting Red Bull Racing to be the team to beat yet again in this weekend's Turkish Grand Prix.
The Milton Keynes-based squad has taken the lead in the championships after two dominant wins in Spain and Monaco, both won by Australian Mark Webber.
Red Bull will introduce an F-duct system this weekend, and that could help extend its advantage even further.
If the F-duct works, McLaren driver Hamilton fears Red Bull will be out of reach again.
"I've heard Red Bull have got their new F-duct, or whatever you guys like to call it, so it's going to be interesting to see if it works and whether or not they see the benefits like we do," Hamilton told reporters in Istanbul on Thursday.
"If so, then it's going to be harder to catch them this weekend. I've also heard Ferrari have some more updates, so potentially it will be those two we are fighting.
"But we've a new rear wing, a slightly newer front wing, so hopefully they will help us edge closer.
"We really don't know until we get into the weekend. We know Red Bull are fastest at the moment, and we haven't done anything major to catch that gap.
"But we have things in the pipeline, and I'll be excited when those come through."
Team-mate Jenson Button said he was upbeat about his chances for the weekend, as he reckons the track will suit his McLaren.
And the world champion also reckons Red Bull will need time before it gets the F-duct working properly.
"It is an aero track but I think our car will work well at this aero level," said Button. "I am much happier coming here than I was going to Monaco or even Barcelona. I think our car, the characteristics and the aero package that we have here, will work well for this circuit.
"It has a long straight, which is good, and the thing that you call the F-duct, we call it something else, should work well around here.
"I know that Red Bull has a system that it will be using this weekend, but we also know it takes a bit of time to tune - and hopefully they will be playing around with that all weekend while we concentrate on set-up."
Button, however, is aware that Red Bull is currently untouchable unless it makes mistakes.
"I think every team has made mistakes this year. One team does stand out as being quick in qualifying and the race, and that is Red Bull Racing. They have qualified on pole position at every race, but they have come away with only three victories. They have made mistakes, but so have we.
"They showed in the last two races that when they don't make mistakes, and don't have reliability issues, they are pretty tough to beat. At Barcelona and Monaco, nobody else had a look-in really - and with safety cars you can't overtake anyway.
"But as long as you get the pitstop strategy right, which is easy when you are leading, nobody is able to touch them. And that is the way it has looked the last two races. I hope it is not the same here, we have to wait and see."