Christian Scaroni won stage 16 of the Giro d'Italia while Isaac Del Toro wobbled but clung on to first overall as several contenders fell or faltered on a crash-filled day in the Alps.

One of those was the former winner Primoz Roglic whose troubled Giro ended in abandonment after a fourth crash in this year's race. Richard Carapaz was also involved but picked himself up to carry on.

Scaroni and fellow Italian and Astana team-mate Lorenzo Fortunato, the two survivors of a long breakaway, crossed the line holding hands at the end of a mountainous 203-kilometre push from Piazzola sul Brenta to San Valentino.

"We spoke about it. He said he would give the stage to me. He's an incredible mate," said Scaroni.

Scaroni became the first Italian to win a stage on this year's Giro, while Fortunato tightened his hold on the king of the mountains classification.

Behind them, Carapaz, Derek Gee and then Simon Yates, one after another, launched late attacks that Del Toro could not match.

The 21-year-old Mexican plugged away and did enough to save his pink jersey, but his overall lead dropped to 26sec over Yates and 31sec over Carapaz.

Carapaz, a former Giro winner and Olympic road race champion, has struggled in recent seasons.

"I haven't been healthy the past few years, as well as bad luck with crashes and the like. I just wanted to give it a try again, I'm here to fight and I'm never going to give up," the 31-year-old Ecuadorean said at the finish.

Yates was also happy.

"Things are looking positive, and luckily I had good legs today," he said on his Visma team's social media feed.

On a day when pre-race favourite Roglic, who had started the day in 10th nearly 4min off the lead, crashed out and Juan Ayuso, who had been third overall, cracked, Gee rose to fourth, 1min 31sec off the lead.

Ayuso, in theory the leader of Del Toro's Team UAE, lost the thread on the penultimate climb, Santa Barbara. He crossed the finish line almost 15min after Scaroni and dropped out of the top 10.

- 'Cracked up' -

Two other riders were withdrew on Tuesday after crashes. Josh Tarling of Ineos hit a guardrail and Italian Alessio Martinelli slid across wet the road and into a ravine after falling during a descent.

The 24-year-old was strapped into a stretcher and taken away by ambulance.

RTL

Alessio Martinelli was described as being 'stable' after his crash down a ravine on stage 16 of the Giro / © AFP

"Fortunately, medical tests ruled out fractures, only an injury to the chin and right buttock and was in 'stable' condition," his team, Bardiani, posted on social media after the stage.

On a day of intermittent showers, former Tour de France winner, Egan Bernal of Ineos, crashed on a descent when another rider's rain jacket appeared to become tangled in his wheel. He changed bikes and rode on, climbing to sixth overall.

"It was a hard day. I suffered a crash and it was quite difficult to get the good feeling back," Bernal told his Ineos team's web site. "All things considered, we can say I came away all right."

"The GC has changed quite a lot in just one mountain stage, and there are still three left," he added. "I will keep fighting. Even if I am a bit cracked up."

Wednesday brings a 155km run from San Michele all'Adige to Bormio that organisers rate three out of five for difficulty.

Friday and Saturday offer two five-star days with a string of huge climbs which will decide who can enjoy a triumphal entry to Rome at the end of a flat final stage.