LottoNL-Jumbo’s Primoz Roglic took victory on Stage 19 by 19 seconds, enough to propel the Slovenian into third place overall, 13 seconds ahead of Froome before Saturday’s decisive time trial.
As has been his trademark on this Tour, Thomas put in a late dig in the final few hundred metres, snatching second place and with it six bonus seconds that extend his lead over closest rival Tom Dumoulin to two minutes and five seconds.
Team Sunweb’s Dumoulin may be the world time trial champion, but Thomas will be confident of defending his advantage on Saturday’s 31km race against the clock which will settle the general classification fight.
This was the stage that worried Team Sky more – a 200.5 kilometres test from Lourdes that included over 5,000 metres of climbing and took on the Aspin, Tourmalet and Aubisque.
Thomas never broke as his rivals prodded and probed, but while he looked comfortable Froome was in danger of cracking on the final climb and it was as much as he could do to finish with Thomas and Dumoulin as Roglic cashed in.
The race came to life at the foot of the Tourmalet, as Ilnur Zakarin of Katusha-Alpecin attacked and drew out Movistar’s Mikel Landa, AG2R La Mondiale’s Romain Bardet and Bora-Hansgrohe’s Rafal Majka.
Sky looked unruffled but over the course of the Tourmalet’s 17km, at an average gradient of 7.3 per cent, the quartet pulled more than two minutes clear, and that advantage only grew as they caught the day’s breakaway on the descent.
Landa was second on the virtual classification at that point, within 80 seconds of yellow, but their advantage would begin to tumble as they started to attack one another on the Aubisque.
As the yellow jersey group closed in, Roglic’s team-mate Steven Kruijswijk and then Dumoulin launched attacks.
Thomas was quick to respond but Froome looked in trouble, at one point dropping a full 30 seconds behind as his legs span furiously and his tongue hung out.
The four-time Tour winner needed the help of the tireless 21-year-old Egan Bernal to pace back on, and as he caught the yellow jersey, Landa and Bardet were being brought back.
A terrifying descent followed as they raced down the mountain in poor visibility. It was in the mist that Roglic attacked, and the former junior world ski jump champion launched himself off the side of the mountain to move into the podium places.
Thomas looked in control as he followed his team-mate down the descent and then pulled ahead in the final few hundred metres, hoovering up six bonus seconds to pad what looks to be a commanding lead.
At the end of 31 kilometres of rolling terrain between Saint-Pee-sur-Nivelle and Espelette, we will know who will wear yellow into Paris on Sunday.
Thomas’ time-trialling has come a long way from the days when he used to ride on the back of a tandem with Luke Rowe’s dad in Wales, but he still has work to do to hold off the world champion against the clock, Tom Dumoulin.
Here, we break down their head-to-head record as Thomas looks to defend a lead of two minutes and five seconds.
In the 19 previous times Dumoulin and Thomas have competed in the same time trial, only once as Thomas fared better, finishing seven seconds up on the Dutchman on the 10.1km stage two of Tirreno-Adriatico early last season. Thomas finished eighth on the seafront course, with Dumoulin 13th on a day when the margins were minimal between the top riders.
Both Thomas and Dumoulin were using the race to prepare for the Giro d’Italia, which Dumoulin went on to win while Thomas withdrew following a crash caused by a police motorbike.
What would represent a safe margin for Thomas? Only three out of the 19 previous meetings has Dumoulin taken two minutes or more out of the Welshman, an interesting stat given than in the majority of them Thomas was not riding for his own general classification hopes and, as he put it, occasionally treating the time trials as ‘rest days’ when he could take a breather before resuming domestique duties. The last time the margin was at two minutes, on the 37.5km stage 13 of the 2016 Tour de France, the comparison was hardly fair given Dumoulin was purely hunting stage wins while Thomas raced in support of Chris Froome.
Thomas would give up one minute 50 seconds to Dumoulin in the 54.6km Olympic time trial at the end of that season, but only found out a few days before he would be taking part at all having focused on the road race. With two minutes and five seconds in hand, Thomas will feel confident he needs only avoid incident to keep yellow and become the third British winner of the Tour.
Though a one-to-18 ratio does not look great, Thomas can take confidence from a succession of big results in time trials over the past two years. His first taste of the yellow jersey came with victory on the opening time trial in last year’s Tour, winning the 14km stage around the streets of Dusseldorf by just five seconds from Stefan Kung. A couple of months earlier, Thomas had been second to Dumoulin, 49 seconds back, on the 39.8km individual time trial in the Giro d’Italia, just a couple of days after crashing heavily. He would withdraw from the race with his injuries after stage 13.
And if Thomas was not wearing yellow on Saturday, he would be in the British national champion’s jersey after winning the 39.7km time trial at Kirkley Hall in June.
Team Lotto-Jumbo’s Roglic clinched his second stage victory in this year’s race with his win on Friday. The Slovenian finished 19 seconds ahead of Team Sky’s Thomas who claimed second place to consolidate his grip on the yellow jersey.
Former ski jumper Roglic has now moved to the third position overall in the leaderboard behind the Netherlands’ Tom Dumoulin – who finished sixth on the stage – in second place. Thomas still holds a 1min 59sec lead over Dumoulin and a 2min 24sec lead over Roglic as the prestigious race heads towards the 20th stage.
Team Sky’s Chris Froome is in fourth position overall.