By Alan Baldwin
MANAMA (Reuters) - Sebastian Vettel celebrated Lewis Hamilton's lucky number on Sunday, the Ferrari driver taking his 44th Formula One victory to go top of the standings while the man in car 44 kicked himself for costly errors.
Hamilton, who has been upbeat about the battle of champions and the fight his Mercedes team have on their hands, appeared more subdued as mechanics cleared the Bahrain Grand Prix paddock.
"Over the years, nothing changes in terms of (how) I feel pain in my heart," said the triple champion.
"People go, like, 'you finished second, you should be happy'. That's not what why we exist. So if anyone ever thinks that any driver, or I, should feel happy with second... I don't know what to say."
After three races, Hamilton is 2-1 down to Vettel and seven points adrift of the German four-times world champion in the standings.
The 32-year-old Briton said he had felt good on the podium, where he was joined by Mercedes team mate Valtteri Bottas, but the mood had changed as the evening wore on and he relived what went wrong.
A five-second penalty for driving too slowly as he entered the pits for his first stop, a move that prevented Red Bull's Daniel Ricciardo getting ahead while the Mercedes pair queued up, was his own fault.
"Supposed to have a five-second gap and I think I had a four-second gap. Just a misjudgement from myself," he said.
Hamilton had missed out on a seventh successive pole on Saturday, with Bottas beating him to it.
"I lost half a tenth out of the last corner. I should have easily been on pole," he said.
"Today, I lost position at the start. Solely my fault. Then the time lost in the pitlane. You practise and practise and practise but you only have 20 opportunities this year and if you mess up it's painful.
"There's no other way of saying it... I try to handle it the best way I can but it eats you up a little bit inside and you've just got to end up trying to cope and move forwards."
Hamilton also finished second to Vettel in the Australian opener, before winning in China, and he said that defeat had not been due to any "massive fault of my own" but rather due to heavy tyre wear.
In Bahrain, the Briton recognised he could have put himself in a much better position to win.
"It's small percentages now," he said of the difference between success and second. "Which I think is what racing should be about."
(Editing by Clare Fallon)