Leading Australian rider Jay Vine has been taken to hospital after suffering serious injuries in a bad mass crash at high speed in the Itzulia Basque Country race in Spain.
Reigning double Tour de France champion Jonas Vingegaard was also hospitalised after the crash.
Vine, who rides for UAE Team Emirates, was diagnosed with a fractured cervical vertebra and two fractures in his thoracic spine.
"Fortunately, there were no neurological problems and there are no other serious injuries or skull injuries," the team said in a statement.
The 28-year-old Australian will remain in hospital for neurological observation and is awaiting orthopaedic assessment of his spine and further treatment.
Vingegaard was reported by his Visma-Lease a Bike team to have suffered a broken collarbone and several ribs, but was "conscious" after the alarming crash, which threatens his hopes of a famous treble in July.
Vine, last year's Tour Down Under winner, also ended up crashing heavily in a concrete ditch and was also taken away by ambulance.
It was a disastrous day for another modern-day great too, with Remco Evenepoel, the 2022 world champion, managing to walk away from the crash despite suffering what his Soudal-Quick Step later confirmed was a fracture to his right collarbone and to his right shoulder blade. He will need surgery on Friday in Belgium.
Giro d'Italia champ Primoz Roglic, who had been the overnight leader, also abandoned the race after giving a thumbs-up to cameras from the BORA-hansgrohe team car to show he was fine.
In all, 12 riders near the front of the peloton were involved in the crash, which happened with about 35km left of the fourth stage between Etxarri Aranatz and Legutio, in northern Spain..
The leaders were making a sweeping right-hand turn on a slight but swift descent, with some sliding off, sending others off the road too into the ditch.
Denmark's Vingegaard, who has been in spectacular form and was favourite for the 2024 Tour de France, had to be carried to the ambulance in a neck brace and needed oxygen after treatment at roadside by doctors.
The race was then neutralised until the finish, with only the six riders who had been at the front being allowed to sprint for the finish to try to win the stage, victory eventually going to the underwhelmed South African Louis Meintjes, who admitted it was a hollow triumph.
"It's a sad day. I wish all the guys who crashed all the best and wish them a fast recovery," Mattias Skjelmose, who took the overall race lead from Roglic, said at the finish.
"My mind is with the guys who crashed, and right now I am not thinking about the leader's jersey."
The crash, which featured three of the world's most outstanding riders in Vingegaard, Evenepoel and Roglic, was also a huge blow for Vine, who has graduated from riding a turbo trainer in his living room to being a peloton star.
He had begun the week-long race on Monday with an exceptional time trial that left him second behind only Roglic at that stage, and revealed afterwards that the Itzulia had been only a late addition to his schedule.
Earlier on Thursday, Roglic's teammate at BORA-Hansgrohe Lennard Kamna was reported to be in a "stable condition" in intensive care after he had collided with a car during a training ride in Tenerife.
