• Wiggins goes fourth after stage 18
• Contador wins time trial to increase his lead

“Time is my everything,” Bradley Wiggins tapped out on his Twitter site a couple of hours before the start of race today’s against the clock, quoting Ian Brown, the former lead singer of the Stone Roses, but it was not destined to be a day on which the clock became his plaything.

After losing the advantage of a promising start to a 40km time trial around Lake Annecy, however, he did well enough to ensure that he ended the day in fourth position in the general classification of the Tour de France, two places above his standing when he rolled down the starting ramp.

The time trial is his speciality, its disciplines honed during his reign as the world’s finest individual pursuit rider, and the course, including a third-category climb, appeared to be made for him. But, like all the contenders for the overall victory, he was outshone by a staggering ride from Alberto Contador, who took over the maillot jaune in Verbier last Sunday and used today’s stage 18 to make it virtually certain that he will wear it all the way to Paris this weekend.

Starting last, Contador was a yellow-clad streak of lightning cutting through the heavy air on a day when thunder rumbled in the surrounding mountains. Much earlier in the day the Swiss rider Fabian Cancellara, the Olympic time trial champion, set an impressive time of 48min 33sec and appeared to have secured a repeat of his victory in the opening stage in Monaco. But when Contador arrived at the first check-point, after 18km, the stopwatch suggested that he was moving in another dimension.

Inevitably his exertions took a toll, and his margin over the field gradually diminished as he circled the lake, but he came home in a time three seconds faster than that of the Swiss rider, with Wiggins, the closest of the challengers to his overall leadership, a further 40sec behind.

It was a demonstration worthy of his compatriot Miguel Indurain, a prodigious time trial performer who won the Tour five times in a row between 1991 and 1995, and on Sunday there will surely be a second victory in three years for Contador.

He explained that he had eased up towards the end of Wednesday’s stage, when he and the Schlecks were climbing the Col de la Colombière, in order to conserve his energy for the time trial. “That was an important factor,” he said.

He had started off thinking only of preserving his leadership, but when he saw his time at the top of the hill he decided to go for the stage win. “I knew Cancellara had gained a lot of time on the descent,” he said, “so I focused on going down the other side of the climb as fast as possible.”

The Schleck brothers, whose combined assault on Wednesday had lifted them to second and third places overall, experienced mixed fortunes. Neither is a time trial expert but, while the elder, Frank, lost 2min 34sec to Contador and dropped to sixth in the standings, the younger, Andy, limited his deficit on the day to 1min 45sec and held on to his second position, now 4min 11sec behind the yellow jersey, as a reward.

“I didn’t lose too much,” the 24-year-old Luxemburger said with a relieved smile at the end of a day that might have brought much worse news. He emphasised that he and his brother are looking forward to Saturday, when the race’s penultimate stage takes the riders up the Mont Ventoux, where they will again be hoping to use their climbing skills to isolate and attack Contador.

On the day Lance Armstrong announced that the principal sponsor of his new team will be RadioShack, a US chain of electronics stores, the seven-times winner failed to respond to signals and could finish no higher than 16th, 1min 30sec behind Contador. Frank Schleck’s bad display, however, lifted Armstrong to third place in the standings, 1min 14sec behind the younger Schleck but now a mere 11sec ahead of Wiggins.

The Englishman’s performance was clearly compromised by his earlier labours in the Pyrenees and the Alps, where he kept pace with the world’s greatest climbers. He was always likely to be presented with a bill, and it arrived on the Côte de Bluffy where he began to struggle.

His start had been fast enough to raise hopes of an ideal way to celebrate the 50th anniversary of the last time the Tour stopped by the side of this lake in the Haute-Savoie, when a stage from Annecy to Chalon-sur-Saone was won by Brian Robinson. That day the Yorkshireman was following up his achievement of the previous year when he had become the first British rider to win a Tour stage.

Wiggins has yet to join the list of Britain’s Tour de France laureates, but one of them, his current Garmin-Slipstream colleague David Millar, did not stint with his praise. “If you’d asked me three years ago whether Brad would have been in contention going up the mountains, I’d have said no,” the Scot announced after coming in with a time good enough for fifth place on the day, two seconds ahead of Wiggins. “But after seeing his determination and how hard he’s worked to be in such great physical condition, I’m proud to call him a team-mate. He inspires me.”

Saturday’s rolling stage from Bourgoin-Jallieu to Aubenas is likely to be a day of recovery rather than inspiration for those still in contention for a place on the podium, before the Giant of Provence discloses how much Wiggins, Armstrong, Andy Schleck and Andreas Kloden have left in the tank. The man in yellow, however, appears to be away and gone.