As the Russian Prime Minister Vladimir Putin stepped into the ring at Moscow's Olympic Stadium to congratulate Fedor Emelianenko, the winner of a martial arts clash on Sunday evening, boos and whistles rang out in the arena.
A moment of shock flickered across his face as he registered what was happening, before he regained his composure and carried on as normal. Nobody can remember anything like it happening before, and one blogger called it "the end of an era". The frosty reception from thousands of ordinary Russians will raise further alarm that discontent with Russia's ruling elite and Mr Putin himself is growing, ahead of elections in a fortnight's time.
The parliamentary elections on 4 December will set the stage for March presidential elections, in which Mr Putin has said he will stand, ending a four-year break during which he moved to the prime ministerial post but remained the most powerful man in the country. In the absence of a credible opposition and with control of the airwaves, Mr Putin is guaranteed to win, but analysts say his support is sliding, and offer the booing as the latest piece of evidence.
Mr Putin's supporters rushed to offer explanations for the hostile reception. Some said it was meant for the defeated American fighter Jeff Monson, who was leaving the arena just as Mr Putin appeared on the scene.
Others, less plausibly, claimed that the whistling was due to the fact that many of the crowd needed to go to the toilet. But in a telling sign, state-controlled television, which showed the fight and Mr Putin's speech live, edited out the whistling and played a more neutral crowd soundtrack during repeats of the speech. A video of the incident with whistling and booing clearly audible, garnered over half a million hits on YouTube within 24 hours.
Polls show Mr Putin's approval ratings, while still high, have slipped by several percentage points since he announced that he planned to return to the Kremlin two months ago. Experts say that after 12 years in charge, his promise of political stability and his macho image may hold less appeal. There have also been voices of discontent over the preparations for next month's parliamentary elections, with allegations of pressure and fraud to ensure that Mr Putin's United Russia wins a respectable majority.
Another clip doing the rounds on the Russian blogosphere is a speech given in parliament last week by the MP Gennady Gudkov. "Our elections are a mix of abuse of administrative resources and work going ahead at full speed to ensure falsification," Mr Gudkov alleged, in a short but fiery speech that was unusual for Russia's rubber-stamp parliament, once famously described as "not a place for discussion".
Mr Gudkov, an MP from the Just Russia party, continued with accusations that doctors, teachers and other state workers are being forced to vote for Mr Putin's United Russia.