The Woking team ended its troubled three-year relationship with Honda and switched to Renault power this year, but suffered reliability problems in testing.

McLaren was embroiled in a tight midfield battle in the season-opening Australian Grand Prix and slipped down the pecking order in Bahrain qualifying, which left racing director Eric Boullier “astonished”.

Fernando Alonso and Stoffel Vandoorne fought back to score a second double-points finish in two races but Boullier told Motorsport.com it was “definitely” a harder start than anticipated.

“We have good race pace, which helps us to recover, but we have been benefitting from race circumstances,” he said.

“We took points we had to take, we did a good job to recover on reliability [from pre-season], so the guys did a good job at the factory.

“Now we need to put everything in place on Saturday and Sunday.”

McLaren’s results have been boosted by teams like Red Bull and Haas throwing away big point-scoring opportunities.

Boullier admitted it was a slightly “funny” position to be third in the championship and said “in some way I should be relieved” with the result.

However, after the race he was “still unhappy” with the team’s second successive poor Bahrain GP, the home race for its biggest shareholder, Mumtalakat Holding Company - Bahrain's sovereign wealth fund.

“We just miscalculated the weekend in terms of set-up,” said Boullier. “It’s a mistake we’ve done and we don’t want to repeat it.

“We need to be where we believe we should be and can’t have too many mistakes like this.”

Alonso declared after Australia that McLaren could forget the midfield and target Red Bull, but admitted in Bahrain that would not be possible until the MCL33 received crucial developments.

“The car we have here on the track and the car we are developing at the factory is different,” said Alonso.

“That car is fixing all our weakness, so we need to bring that car as soon as possible.”

Boullier insisted he had “100%” confidence in McLaren’s technical team, and explained that part of its Bahrain troubles was getting the most out of the tyres and the cars carrying too much downforce.

McLaren’s pre-season reliability woe forced it to alter its updates schedule, and Boullier added: “That’s why we have a lot to come and that’s why I think Fernando is so positive in terms of upgrades and the next few races.

“Hopefully that will be enough to clear it [the midfield].”

McLaren’s old engine partner Honda scored the best finish of its F1 return with Toro Rosso’s fourth place, besting any result in McLaren-Honda’s three years together.

“We always said we wish the best for Honda and they had a good car [in Bahrain],” said Boullier.

“They made no mistakes and they were fourth, which is good. Well done.”