Currently seventh overall, the Kazakh is by far the most anarchic and unpredictable of all the principal contenders on this year's Tour. Even if his condition is not as good as in 2003, when he finished third overall, the 31-year-old's tendency to attack at the slightest provocation has gained him huge popularity.
Yesterday, with the stage win already the property of Armstrong's team-mate Paolo Savoldelli, Vinokourov, none the less, charged off from a second group containing Armstrong at the foot of a tiny climb prior to the finish town of Revel.
In terms of strategic planning, his manoeuvre was as illogical as it was ineffective: Armstrong promptly romped past him.
The egg was on Vinokourov's face but there have been other times when his aggression has been invaluable: a similarly uncalculated attack earned him T-Mobile's only stage win of the race, after a mammoth slog through the Alps a week ago, and will certainly make him a force to be reckoned with next year.
This year, forming part of T-Mobile's three-pronged strategy, where he shared power with Andreas Klöden and Jan Ullrich but has been working for the 1997 Tour winner, has effectively cramped his style. Next July, with Crédit Agricole his most likely destination, he will have a chance to come into his own - or fall flat on his face. Either way, it should prove entertaining.
T-Mobile yesterday also had to come to terms with Klöden's untimely departure from the Tour. Nursing a fractured wrist caused by a crash on Tuesday, the 2004 Tour runner-up rode 10 kilometres before climbing into a team car.
The rest of the bunch had rather longer to wait, more precisely another 220 kilometres in searing temperatures touching 40 degrees in the shade: Armstrong has often defined cycling as an exercise in pointless suffering. Yesterday, as the Tour tackled its longest stage over largely flat, bland terrain, it must have felt more pointless than ever.
The Texan, though, had reasons of his own to celebrate - and not just because he has now led the Tour for 79 days during his career, one more than the French legend Bernard Hinault. Rather, his delight was due to Savoldelli's impressive stage victory, the second for an Armstrong team-mate in this Tour and the third for the squad.
Part of a day-long break of 17, the Italian outwitted late attacks from Kurt Asle Arvesen and the Australian Simon Gerrans to take his first Tour stage win. "It was incredible," Armstrong said. "For Discovery, the Tour just keeps getting better and better."
But the race's and the team's final celebrations in Paris, however, will be for the Texan and the Texan alone.
Alasdair Fotheringham writes for 'Cycling Weekly'
Pau-Revel (239.5km, 147.8 miles): 1 P Savoldelli (It) Discovery Channel 5hr 41min 19sec; 2 K-A Arvesen (Nor) CSC same time; 3 S Gerrans (Aus) Ag2r-Prevoyance +8sec; 4 S Hinault (Fr) Crédit Agricole +11; 5 A Grivko (Ukr) Domina Vacanze +24; 6 O Sevilla (Sp) T-Mobile +51; 7 B Tankink (Neth) Quick Step s/t; 8 D Righi (It) Lampre-Caffita +53; 9 S Dumoulin (Fr) Ag2r-Prevoyance +3min 14sec; 10 A Davis (Aus) Liberty Seguros +4.10.
Overall: 1 L Armstrong (US) Discovery Channel 72hr 55min 50sec; 2 I Basso (It) CSC +2min 46sec; 3 M Rasmussen (Den) Rabobank +3.09; 4 J Ullrich (Ger) T-Mobile +5.58; 5 F Mancebo (Sp) Illes Balears +6.31; 6 L Leipheimer (US) Gerolsteiner +7.35; 7 A Vinokourov (Kaz) T-Mobile +9.38; 8 C Evans (Aus) Davitamon-Lotto +9.49; 9 F Landis (US) Phonak +9.53; 10 C Moreau (Fr) Crédit Agricole +12.07.
Points: 1 T Hushovd (Nor) Crédit Agricole 164pts; 2 S O'Grady (Aus) Cofidis 150; 3 R McEwen (Aus) Davitamon 142; 4 A Davis (Aus) Liberty Seguros 101; 5 Vinokourov 97.
Mountains: 1 Rasmussen 185pts; 2 O Pereiro (Sp) Phonak 135; 3 Armstrong 92; 4 M Boogerd (Neth) Rabobank 90; 5 Moreau 89.