A sensational Tour de France is set to conclude in Alberto Contador's favour in Paris tomorrow, but the Spaniard's third victory in four years is likely to be a tainted one in many people's eyes.
Andy Schleck said on Wednesday's rest day in Pau that the Tour would not be decided by a chain slipping.
He was right - had Contador waited for his rival on the ascent of the Port de Bales on Monday's stage to Bagneres-de-Luchon, the duo would be level on time entering tomorrow's final day.
The 39-second swing Contador garnered - contrary to racing etiquette - by surging forward when his rival suffered a mechanical problem was cancelled out on today's 52-kilometre penultimate day time-trial from Bordeaux to Pauillac.
Contador (Astana) entered today's 19th stage with an eight second lead over Schleck (Team Saxo Bank), but finished 31 seconds ahead of the Luxembourg rider on the route through the vineyards north of Bordeaux.
The Spaniard finished in one hour six minutes 39 seconds, with Schleck clocking 1hr 7mins 10secs.
Barring a freak accident or illness, Contador will step on to the top step of the podium and add to his 2007 and 2009 titles on tomorrow's 102.5km 20th stage from Longjumeau to the Champs Elysees, which traditionally is a procession for the peloton and ends in a sprint finish.
World and Olympic time-trial champion Fabian Cancellara (Team Saxo Bank), who won the Rotterdam prologue on July 3, clocked 1.00:56 to win today's stage, but Contador was the real victor.
Schleck was angered by the circumstances in which Contador took the maillot jaune, but accepted his rival's apology before attempting to overhaul him on Thursday's final Pyrenean stage.
The duo were inseparable in an epic duel up the Col du Tourmalet, handing Contador - the more accomplished practitioner against the clock - the advantage.
Schleck, the 2009 Tour runner-up to Contador, finished 116 places and 42 seconds behind Contador in the 8.9km prologue which began the Tour.
Contador rolled down the starting ramp three minutes behind Schleck, who put in a sterling effort today.
Unofficial time checks showed Schleck's maximum time gain at five seconds - putting him three behind Contador overall.
But the 25-year-old Luxembourg rider faded and Contador pressed forward to enhance his hold on the maillot jaune.
The 27-year-old Spaniard was relieved with his success, which is set to be confirmed tomorrow.
"I am very excited because it was a victory that was difficult to attain," said Contador, who also won the title in 2007 and 2009.
"It had not been easy in 2007 and last year, but it's unbelievable - it's a huge relief."
Contador admitted to finding today's time-trial, played out in strong winds, tough.
He said: "Today we can say that I suffered.
"I think Andy has also suffered a lot for the race was very difficult.
"This was not my best day and I had doubts, but I won."
The smallest winning margin in Tour history was eight seconds when Greg LeMond finished ahead of Laurent Fignon in 1989.
Contador was involved in the next closest finish in Tour history, when he defeated Cadel Evans by 23 seconds in 2007.
But had Contador not taken the lead when Schleck's suffered his mechanical problem, the duo would be on the same time entering tomorrow's final day.
As it stands, the margin between the duo is the fifth smallest in Tour history.
Schleck was diplomatic today.
"I don't care what the time difference is," he said. "What counts is what place you have at the end, and Alberto was just better than me this year, but I'll be back.
"After over 3,500 kilometres, 39 seconds is not a lot.
"I've won another white jersey, two stages and I believe it's been pretty successful Tour."
Denis Menchov (Rabobank) finished 11th today to overtake Samuel Sanchez (Euskaltel-Euskadi) in the race for the third and final podium place.
Seven-time champion Lance Armstrong (Team RadioShack) was 67th today but held on to 23rd place overall by four seconds ahead of Bradley Wiggins (Team Sky), who was ninth today.
Armstrong finished third behind Contador and Schleck in 2009, with Wiggins fourth, but both have endured difficult Tours.
Armstrong will tomorrow bow out of his distinguished career by completing his 13th and final Tour in Paris.
With the yellow jersey seemingly secured, tomorrow the focus will turn to the points classification's green jersey.
Alessandro Petacchi (Lampre-Farnese) is currently in possession of the maillot vert on 213 points, with Thor Hushovd (Cervelo Test Team) 10 points behind and Mark Cavendish (HTC-Columbia) six points further adrift.
Cavendish - a winner of four stages so far in 2010 - has an outside chance of taking the green jersey for a first time, if he can win on the Champs Elysees for a second successive year.