McLaren fears that last week's disappointing race in Malaysia will be the first of many if they fail to dramatically improve their MP4-29 in the coming weeks.
After their double-podium finish in Australia, Jenson Button finished sixth and his McLaren team-mate Kevin Magnussen in ninth place at Sepang last week.
With those results in mind, as well as the tempo with which the Woking team's rivals are improving their cars, McLaren racing director Eric Boullier fears for the worst at this week's Bahrain Grand Prix.
"I don't think it's going to be a one-off, that's the problem," Boullier told Autosport ahead of this week's race at Sakhir.
"We said in Melbourne we were happy with the result because we had been opportunistic.
"But obviously we knew the others were going to massively catch up once they started to fine-tune their balance and ride and everything on their cars, especially the electronic parts. It's exactly what happened."
"This is the down spiral when it's very hot.
"Our lack of downforce is making the car slide more and when the car slides more the tyres get hotter, and if you pass the limit of the surface temperature you get in trouble.
"This is exactly what happened to us. It was very hot and we were struggling with the grip.
"Strangely there was not much reliability issue here [in Malaysia], and it's true our strategy to be reliable was good in Melbourne and here it didn't pay off because most of the cars saw the chequered flag.
"We know performance-wise we have to massively catch up and aggressively develop the car."
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