After announcing the decision to disqualify Nibali, the race director said he had "never seen anything similar" to the Italian's decision to hold onto an Astana team car, and lamented the rider's "regrettable attitude".
Nibali took hold of Astana's turquoise team car with 16 kilometres left to be able to join the leaders' group. He made it, but later lost contact on the closing climb to Caminito del Rey.
He finished in 31st, at 1-38 minutes down from stage winner and new overall leader Esteban Chaves (Orica-GreenEDGE), and 1-02 back from top favourite Nairo Quintana (Movistar) – but his result is now null after the decision to expel him from this year's Vuelta.
After the race jury saw the video of the incident, it sent the Sicilian home along with the sports director, Alexandre Shefer, who was driving the car.
"We've seen the video. They tried to search in the rules, all the possibilities, but you know the decision, to expel the rider," Vuelta race director Javier Guillén told journalists after the stage finish.
"I agree with the decision, because I think his attitude is regrettable."
Nibali won the Vuelta in 2010 and the other two grand tours – the Giro d'Italia in 2013 and the Tour de France in 2014. He was one of the big stars to line up when the race began yesterday in Marbella along with Chris Froome (Team Sky), Quintana, Tejay van Garderen (BMC Racing) and others.
He is no stranger to controversy, however. At the Tour, he blamed Froome for a crash in the first week. In the final week, he attacked to an eventual win on the La Toussuire mountain stage, while Froome in the yellow jersey had a mechanical problem.
On the roads through Andalusia, Nibali crashed with several others at 30 kilometres to race in the 158.7-kilometre stage. He chased with his team-mates, but hovered around 1-34 minutes with 20 kilometres left to go. Putting his hand on the car door meant that he closed the gap quicker, but he had to face the consequences when the jury saw the YouTube video making its way around the internet.
"There is no other possibility — this image is bad for cycling, for the sport. The consequences of this decision are bad for the Vuelta, we have lost a big rider," Guillén continued.
"Any other decision would be hard to understand. The rules have to be followed. We have seen the images, I have never seen anything similar before. We respect the UCI jury's call on this — we are sorry for what has happened."
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