Barcelona, Spain - A frustrated Fernando Alonso let rip at McLaren's engine partners Honda on Wednesday after another difficult afternoon of pre-season testing.
Spanish and Italian media quoted the former double Formula One world champion as saying that everybody in the team was ready to win "apart from Honda".
Alonso left no doubt about his state of mind after ending the day 12th of the 14 drivers in action and with only 46 laps on the board - less than a race distance - compared to 102 for Red Bull's Max Verstappen.
"Tough, tough test so far - the first week and this week," he said. "We need to improve right now if we want to arrive in Australia ready.
"We are not fully ready to complete a Grand Prix yet," continued Alonso. "The power unit has too many problems that we need to deal with... we cannot say that we are happy. We are frustrated and disappointed.
"I am driving at my best... I feel the best driver out there, I just need an engine that can run as quick as the others on the straights."
Alonso estimated McLaren was giving away 30km/h to rivals on the straights and it was hard to have a real feeling of the car with so few laps strung together.
"It is not a surprise, last week was not ideal for us," he said. "Today more or less we knew we were in front of a tough day so we tried to learn as much as we can."
Honda's return to Formula One in 2015, when they renewed a previously successful partnership with former champion McLaren, has been traumatic.
In 2015, McLaren had its worst season yet, finishing ninth overall with just 27 points after suffering endless reliability problems with the power unit.
It finished sixth in 2016 with 76 points but still no closer to winning a race for the first time since 2012, but had raised hopes for 2017 after the rules on engine development were relaxed.
Testing so far has been more reminiscent of 2015, although Alonso said the situation was different because Honda had far more data to work on.
"Probably this year is a bit more frustrating,' he said, "because the change of regulations and things like that, you have higher hopes when you think you can close that gap over the winter."