Australian Kaden Groves won a frantic sprint to take stage 11 of the Vuelta a Espana on Wednesday as Remco Evenepoel maintained his overall lead on a day dominated by further rider casualties.

After more big names failed to start following positive Covid tests, Julian Alaphilippe crashed out with less than 70 kilometres to go, dealing a blow to his hopes of a world title hat-trick and to the Vuelta chances of team-mate Evenepoel.

"It's sad on such a quiet stage to lose Julian," said Evenepoel. "It's a stupid fall. I hope he's okay and that he doesn't suffer too much.

"He was in great shape, but I have confidence in all my teammates for the coming weeks."

Groves gave BikeExchange their first victory of this year's Vuelta on the day they lost British team leader Simon Yates following a positive Covid test.

"This morning with the news of Simon going positive for Covid all the boys were pretty disappointed," said Groves after the 191.2km run along the windy Andalusian coast to Cabo de Gata.

"It was the best way to bounce back after such news."

"I'm really happy to celebrate but also wish he was here," said Groves after his first major tour stage victory.

Evenepoel finished safely in the peloton to preserve his 2min 41sec lead over Primoz Roglic but the Belgian lost a key ally in Alaphilippe.

The double world champion left the course in an ambulance after dislocating his right shoulder in a fall with less than 70km to go.

He will fly to Belgium on Thursday for further scans to rule out any further damage, his Quick-Step team said in a statement.

The crash puts 30-year-old Alaphilippe's chances of winning three straight world championship road races in doubt. This year's event is in Wollongong, Australia, on September 25.

Among the Covid casualties was Irish sprinter Sam Bennett of Bora, who dropped out Tuesday. He had been a close second in the points competition after winning two stages earlier in the race.

Sprint leader Mads Pedersen suddenly had a big advantage but needed to collect as many points as possible on flat finishes with second-place Evenepoel a threat in the coming mountain stages.

Pedersen collected maximum points in an intermediate sprint with 10km to go, but was outmanoeuvred in the massed charge for the finish line. The Dane ended up fifth after being boxed in.

"It was pretty fast, a lot of guys everywhere," the Trek rider said. "I misjudged it a little bit."

Groves outpaced Dutchman Danny van Poppel and Belgian Tim Merlier to the line.

'Paranoia'

Alaphilippe was the latest casualty in a Vuelta that has been hit unusually hard by crashes and Covid positives.

Quick-Step had lost another rider, Pieter Serry, to a positive Covid test on Sunday.

After Yates, the 2018 Vuelta champion, Pavel Sivakov of Ineos, who was also in the top 10, and three Kern Pharma riders withdrew before Wednesday's 11th stage, the day's racing began with ony 154 of the 184 starters.

"There is a little paranoia among the riders," said Colombian Miguel Angel Lopez. "We see that every day several teams are starting without all their riders. We have to be pay a lot of attention and wear the mask and continue to respect the rules."

On Thursday, riders travel 192.7km through Andalusia on a stage that is mostly flat until a demanding 19km finishing climb up Penas Blancas.