The Briton aborted his final qualifying lap at the British Grand Prix, only for Mercedes team mate and title rival Nico Rosberg to push on and seize pole position in another significant psychological blow.
On provisional pole and with the track wet in places, Hamilton assumed he could not improve on his lap time. So he pitted.
Rosberg, behind, figured he had nothing to lose by continuing and the championship leader was rewarded when the final sector turned out to be dry and much quicker than before.
So too did others, with Hamilton ending up sixth.
It was his third qualifying error in as many races and one that may come to define his season with the Briton looking out-thought as well as out-fought.
With retired triple world champion Jackie Stewart questioning the driver’s ‘mind management’ skills, Hamilton cut a subdued figure afterwards.
“I made a mistake today and pulled out of the lap when I should have kept going,” he told reporters. “It was my decision, a bad call, and that decided my qualifying.
“It just didn’t feel good. No other reason for it,” he replied tersely when asked why he had decided not to finish his final lap.
Hamilton went into the last race in Austria talking of damage limitation, after a quick lap was ruled out for exceeding the track limits and left him starting ninth, and he was at it again on Saturday.
“I feel tomorrow is going to be damage limitation again,” he declared. “But we’ve got 100,000 people here tomorrow so hopefully they will energise me.
“I’ve got a lot of Mercedes (powered) cars ahead which are going to be very hard to overtake, it’s not going to be as easy as it was in the last race…but anything is possible here as we’ve seen in the past.
“I’ve never in my life ever given up and today wasn’t a case of giving up,” added the 2008 champion.
“I just chose not to do the lap as it wasn’t feeling right. It wasn’t feeling like it was going to be quicker.”
Hamilton said he had no information from the team that the last sector was going to be four or five seconds faster than previously although that was not their fault.
Asked what he would have done in Hamilton’s shoes, Rosberg remained diplomatic even though he admitted he was surprised the Briton had backed off with his team mate right behind.
“It was such a messy qualifying, so many situations that you just can’t foresee,” he said. “So many variables coming in, you can’t consider all these things. Both decisions were reasonable at the time.
“It’s easy afterwards looking from the outside but in the car it’s all over the place and so many things going on and you don’t know how the rest of the lap is going to go.”
(Editing by Tony Jimenez)