SPA-FRANCORCHAMPS, Belgium (Reuters) - Lewis Hamilton chose the wrong wing for his McLaren at the Belgian Formula One Grand Prix on Saturday and then got into more of a flap trying to explain himself on Twitter.

McLaren Formula One driver Lewis Hamilton of Britain stands in the pit during the third practice session of the Belgian F1 Grand Prix in Spa Francorchamps September 1, 2012. REUTERS/Francois Lenoir

The 2008 world champion qualified seventh, with team mate Jenson Button on pole position, after opting to run an older specification rear wing on his car instead of the latest one his fellow Briton went with.

"Damn. Jenson has the new rear wing on, I have the old. We voted to change, didn't work out. I lose 0.4 tenths (of a second) just on the straight," he said on his Twitter feed soon after qualifying.

"Nothing I could do. Now it's about picking up every point I can from there. Jenson should win easy with that speed.

"Can't change the car once qualifying starts. I hope Jenson brings home maximum points. I'll try & support him," said Hamilton before the tweets were swiftly deleted.

Asked about them, and why they had disappeared from his account, Hamilton at first feigned ignorance and then explained to reporters he wanted to "rephrase some things I said".

He then sent out a further tweet after the meeting, with another acronym based on an obscenity he suggested his followers could look up on Google if uncertain, that also subsequently disappeared.

The 27-year-old arrived in Spa mourning a much-loved aunt who died from cancer earlier in the week and some of his online behaviour has raised eyebrows with references to rap music and his 'homies' (friends).

American rapper and music producer Lupe Fiasco is also with him in Belgium.

Hamilton said on Friday, when practice was rained out, that it had been "easy to stray and think about events that have happened over the past week" and he had been taking pictures and tweeting to focus on other things.

The driver won the last race, in Hungary, before Spa and has been quicker than Button generally in qualifying this season but on Saturday he recognised he had got it wrong.

"Just this morning in P3 (third and final practice) I had some instabilities with the wing, the new wing that we were trying," said the Briton.

"At the time we had a relatively big gap between the Saubers and the Red Bulls and the Ferraris and so we felt on our side of the garage that we should try something to fix it."

That meant going with the wing the team had used in Budapest, a tight and twisty circuit very different to the high-speed, flowing lines of Spa.

Hamilton said the theory was the gap between the two wings was not so great "but we proved ourselves wrong. It was obviously the wrong way to go".

He said the decision had been made as a team.

Button, savouring his first pole since 2009 when he was at Brawn GP, had complained in practice about the car's lack of grip and balance but decided against any change of wing.

"I spoke to my engineers and we decided to stay where we are because we thought with the sun out hopefully the circuit would grip up," he explained.

"We thought it was the best option."

(Editing by Tim Hart)

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