“It’s a good question,” said Simon Yates, his words unusually hesitant and imbued with apparent self-doubt. “I don’t know. I hope not. We’ll see.”

As rallying cries go, it was hardly Henry V before Agincourt. Especially given the fact that his interrogator was asking whether the first cracks in his effort to win the Giro d’Italia were beginning to show.

Giro d'Italia 2018: Simon Yates has pink jersey lead cut in half - as it happened Read more

Then again, perhaps Yates’s demeanour was understandable. It had taken him nearly 2,000 miles, across 20 days and two continents, to put together a 56-second lead over last year’s winner Tom Dumoulin – and, suddenly, within a mile of climbing , half of it had vanished into the thin mountain air.

As the speculation swirled through the press box – Is Yates ill? Had he burned up too much of his tank during Tuesday’s time trial? Was he conserving energy? – only one question really mattered: was this a blip or a preview of the final few days of this Giro?

Many of the answers are likely to be found in Friday’s torturous 184km stage from Venaria Reale to Bardonecchia in the Alps. In theory, the vicious ascents should favour a pure climber such as Yates. But the peloton will be probing for weaknesses as soon as they hit the Colle delle Finestre, not only 2,178m high but also up gravelly roads.

There were few signs that Yates was in trouble for much of the 18th stage from Abbiategrasso, a pleasant enough town on the outskirts of Milan, to Prato Nevoso. Indeed for all but two of the stage’s 196km he looked comfortable and content. Ahead of him a pack of 10 riders had established a 16-minute lead over the peloton, but none of them was a danger to him on general classification – including the stage winner Maximilian Schachmann. Dumoulin, meanwhile, was being closely man-marked.

But then the stage and the race was suddenly blown apart. The fracture came in two parts. First Dumoulin attacked, a break Yates rushed to contain. Then Chris Froome hit him again, and Yates found nothing in response. “I couldn’t have closed the gap,” he admitted. “It was not a technical problem. I was just a little bit tired. I couldn’t respond to the final acceleration. And that’s OK. That’s OK.”

Just before Froome went, Yates had looked into Dumoulin’s eyes, trying to seeing how he was coping – and whether he had given everything in one attack or whether he still had his legs. Watching the Dutchman shoot off ahead of him provided an instant answer. “But the next two days suit me more,” Yates insisted. “Thursday was a very explosive effort – one big effort. I don’t think it is my forte.”

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That is true enough, but there were plenty of sceptics among the Italian media who fear that Yates has expended too much energy in winning three stages and picking up several bonuses. But as he pointed out, with some justification, it is being so aggressive that has put him in the lead in the first place. “This is what I needed to do,” he said. “If I hadn’t have been so aggressive then I would have been behind. I’ve taken 40 seconds in bonus seconds in this race so far, and I am only 28 seconds ahead. So for me it has been necessary.”

Froome, meanwhile, who remains in fourth place, 3min 22sec behind, has not given up hope of a shock victory.

Before the stage a large crowd had swarmed around the Team Sky bus shouting “Chris, Chris” and fingers clambered to touch a five-times grand tour winner. During his four Tour de France victories Froome has been doubted, spat at and accused. Here, at least, there was only love.

And with the help of his team-mate Wout Poels, who had headed up the road earlier on the climb, Froome showed signs of his best form.

He explained: “Wout was feeling good so we agreed that he’d push on and see what would happen in the last few kilometres if I could get across to him. It worked out really well.

“I had no idea Yates was on the limit there. Only when I accelerated did I turn around to see Dumoulin with me and not Simon. The race is still on – with two extremely hard days coming up. We’ve got Colle delle Finestre so there’s all still to race for.”

The only positive for Yates on a day when this year’s Giro d’Italia was blown spectacularly apart could be found in the mirror. For both cheeks were still firmly imprinted with rouge lipstick, courtesy of the podium girls at the end of the stage.

“If I finish now I have already had a successful Giro,” he said as he left the hotel. But, having come so close to the Maglia Rosa, he will be desperate to seal the deal.