Terrorists, awkward protests, rain ... what can happen to spoil the coming-out party?

In the minds of Beijing's collectively stressed Olympics organisers, the list of things that could go wrong on the supposedly auspicious eighth day of the eighth month of the eighth year of the century - in other words, tomorrow - is long indeed.

They suffered their latest panic attack on Monday. Police outside a barracks in the Muslim-populated Xinjiang region - which has been at the heart of the country's security fears for the past couple of months - were struck by a truck, then homemade grenades; 16 were killed and another 16 injured.

The officials had another panic attack in the middle of last week. Video of a rehearsal of the opening ceremony - classified a 'top state secret' - became an instant hit on the internet after a reporter from a South Korean television station managed to walk into the National Stadium and shoot two minutes of footage.

The organising committee went ballistic over the footage from the previously low-profile Seoul Broadcasting System, hammering it for lacking journalistic integrity and threatening punitive action. Possibly as a result, nearly all links to the footage vanished overnight, and the broadcaster apologised publicly - as fellow broadcaster CNN and actress Sharon Stone had done following other incidents during the tumultuous run-up to the Games.

Given all the efforts to make the opening-ceremony spectacle a 'massive surprise to the world and satisfying to all Chinese people', in the words of its chief director, Zhang Yimou , the video leak was more than just annoying. It seemed a disturbing but genuine reminder that you never know what can spoil a party. It can be something big or small - hence Beijing's obsession with everything from controlling the weather to micromanaging people's behaviour.

Officials have been trying their very best to anticipate and eliminate any possible challenge to the glorious coming-out party they envisage.