Chris Froome's clear pathway to overall victory in the Vuelta a España blurred a little in the fog of Los Machucos on Wednesday, as the Team Sky leader struggled on the mist-enshrouded, ultra-steep climb and unexpectedly ceded 42 seconds to Vincenzo Nibali (Bahrain-Merida) and 27 seconds to Wilco Kelderman (Team Sunweb).
As the clouds and heavy showers gathered around the 7.2km ascent deep in rural northern Spain, Nibali attacked a third of the way up the climb, and Froome did as expected, opting to follow his own pace. But rather than his usual tactic of then clawing back on a rival's breakaway after initially dropping back, instead Froome saw the time gap stretch steadily open and seemingly even had difficulty staying with his best climbing teammate, Mikel Nieve. He finally crossed the line in 14th place, 1:46 down.
Froome later said that he believed he had paid a price at Los Machucos, energy-wise, for going so deep en route to victory in the Logroño time trial, where he took 57 seconds on Nibali. And despite his defeat, the Briton can draw consolation from the fact that in the sum of his gains from the opening two days' racing in the third week, he is still 15 seconds further ahead of the Italian than he was before the time trial.
However, with the Angliru, a similar climb to Los Machucos, coming up on Saturday, there is some cause for concern that having led the Vuelta since stage 3, the Briton might be in danger of falling at the final fence.
Froome seemed to recover fast from his setback, however, munching away on a bowl of fruit during his leader's press conference and giving a far longer series of answers than in his previous difficult stage, after crashing twice at Antequera. And although he recognised that the efforts of the time trial had taken their toll, he seemed upbeat in general.
"I'm sure I paid a little bit for [Tuesday's] effort, that's clear," Froome told reporters. "We always knew that today's final was pretty tough. But I'm still in a fantastic position, I'm confident and I've got a good buffer of time. The team's looking great, and hopefully I'll bounce back after a hard day today.
"The way I see this part of the Vuelta is as a four-day block, five if you count [Tuesday] and knowing that stage 20 will be the hardest day of the four. Any effort today or yesterday is all going to compound in the grand finale of the Angliru," he said. "I'm optimistic, feeling good about what lies ahead, and the guys in the team are doing really well. I'm confident we can get the job done."
Froome chuckled a little when asked if it was harder for him to win the Vuelta than to win the Tour.
"I've yet to win it and I've won four Tours, so in that sense, sure, it definitely has been harder to win the Vuelta for me," he said. "But that's been because up until now my focus has been 100 per cent on the Tour de France and then just try and survive the Vuelta. This year I started [building up] the season maybe a bit later, and I wasn't quite at my top by the Tour, but that means I've been able to hold my form for longer, and I think that's shown in this year's Vuelta."
It would seem unwise to read too much into one tricky day in the mountains, when Froome has done so well in all of the previous ones in the Vuelta, either gaining time on Nibali or at the worst taking away cycling's equivalent of a score draw. And as Froome has constantly observed, the Vuelta is a race that changes very fast from one day to the next, and on Saturday the boot might be on the other foot and Nibali could be the one to suffer unexpectedly.
Either way, and in perfect keeping with the Vuelta's longstanding reputation for unpredictability, Froome's setback on los Machucos has created a small but significant degree of uncertainty about the final GC result that will only be resolved, now, on the Angliru itself.