Spain's Alejandro Valverde, a key team-mate of one of the race favourites, Colombian Nairo Quintana, is out of the Tour de France after crashing during the opening time trial in Germany on Saturday.
Valverde, third overall in 2015, skidded into a safety barrier after losing control of his bike on a wet left-hand corner on the 14-km course in Düsseldorf.
The 37-year-old was treated by race medics on the spot before being taken to hospital with a suspected leg injury.
Movistar said that Valverde, who had a sterling start to the season with victories in the Liege-Bastogne-Liege classic and the Tour of Catalunya, had been forced to abandon.
"At first we thought it was just a crash, like it happens often, but when we saw that he could not get up, we knew it was serious," said sports director Jose Vicente Garcia. "It is a sad day for us."
Valverde and Quintana were seen as a formidable double act on this Tour, but the Colombian, second overall in 2013 and 2015, will now have to make do without the help of the Spanish veteran.
Reigning champion Chris Froome wasted no time flexing his muscles at the as he powered to sixth place in a treacherous opening time trial won superbly by his Team Sky colleague Geraint Thomas.
Heavy rain turned what, on paper, had looked like a regulation 14-km circuit alongside the River Rhine into an incident-packed Grand Depart that could have major consequences in the three-week battle for the yellow jersey.
Thomas showed brilliant bike-handling as he finished in 16 minutes 04 seconds, five seconds ahead of BMC's Swiss rider Stefan Kueng, who was two seconds ahead of Kiryienka in third.
Froome, the last rider out, was 12 seconds slower than Thomas but significantly quicker than his main GC rivals.
Quintana was 48 seconds slower than Thomas with Australian Richie Porte one second quicker than the Colombian.
Hopes that Tony Martin would mark the first German Grand Depart since Berlin in 1987 with a home win were washed away as he could only manage fourth quickest.
Ireland's Nicolas Roche was one of many riders to crash on the wet surfaces. The BMC Racing Team rider was fortunately unhurt in the fall and was able to remount and complete the 14 kilometre individual time trial. He finished in 122nd place, one minute and 14 seconds behind Thomas .
“It is not great for me,” he said afterwards. “It is a city centre prologue. Obviously the roads are a bit greasy and the rain doesn’t help.
“I am not sure if it was a bit of oil or the tram tracks [which caused the crash], because I fell where the tram tracks were as well. I don’t know when the wheel went first. I am a bit disappointed. I was hoping to do a good prologue, but that is how it is.”
His first cousin Dan Martin had a respectable ride, finishing 57th out of the 198 starters. He was 49 seconds behind Thomas and 37 behind triple Tour de France winner Froome. He prioritised safety over speed in the time trial.
Martin is aiming to improve on his ninth overall in last year’s Tour. As for Roche, his role in the race is as a helper for his BMC Racing Team leader Richie Porte, who is one of the top favourites.
As a result he will have limited personal opportunities in the event.
The race continues on Sunday with a 203.5 kilometre race from Düsseldorf to Liège. Martin’s first targeted stage is on Monday, with Wednesday’s fifth stage also suiting his characteristics.
