With victory for his CSC squad all but certain, Zabriskie had touched wheels with a team-mate near the finish and pitched into the barriers. After bouncing back into the road and spinning a couple of semi-circles, the rider from Salt Lake City ground to a halt, his left side blackened with tarmac, half his yellow jersey and shorts ripped to shreds, and all chance of retaining the lead gone.
His team, keen to protect their main overall contender, Italy's Ivan Basso, and with the stage win still a possibility, could not afford to wait. But after losing the race lead, even that consolation was denied them as they finished two seconds behind Discovery.
Fighting back the tears, Zabriskie crossed the line 1min 24sec later. Had the accident happened a few hundred yards further on in the narrow, twisting streets, Zabriskie would have been benefited from regulations that award all riders from the same team the same time if they crash inside the last kilometre.
Instead, he has slid to ninth overall, while Armstrong, whose team delivered a solid, but not spectacular performance found himself back in yellow.
"It was the kind of tough finish, with turns and twists and the whipping wind in the streets where accidents can happen and when you're riding on the limit mistakes can be made," Armstrong said. The Texan had a fairly stressful run, even with no crashes or mechanical trouble.
"We were timed to start five minutes behind CSC, so it was tough going through the intermediate time checks and not knowing whether we were ahead or behind until five minutes later," said Armstrong, who, it was revealed yesterday, is suffering from a painful knee following a training accident a fortnight ago.
"Until CSC crossed the line we didn't know whether we'd won or not. When we did see we had, there was a lot of hollering and cheering. It's nice to be back in yellow again and win this stage for a third straight time, whatever. Although the real objective was to put time into all our rivals." A fine performance by T-Mobile enabled his arch rivals Jan Ullrich and team-mate Alexandre Vinokourov to lose only 35sec, however.
Already winner of a record six consecutive Tours, Armstrong now owns another piece of history - the fastest average speed on a stage. Discovery averaged 57.38kmh [35.86mph], nearly two kilometres faster than the previous best. And there leader seems to be heading towards win No 7.
Alasdair Fotheringham writes for 'Cycling Weekly'