American cyclists celebrated their national day by continuing their dominance of the Tour de France. Not only is American David Zabriskie (CSC) wearing the leader’s yellow jersey after three stages, but Americans hold four of the top six places in the general classification. Among them is six-time defending champion Lance Armstrong, who sits just two second behind Zabriskie and again looks like the man to beat.

The only country with more to celebrate is Belgium, whose young sensation Tom Boonen (Quick Step) took yesterday’s stage in a bunch sprint after 212 kilometers. It was Boonen’s second consecutive stage win and provided a dramatic demonstration of his prowess; he took the center line and blew past his rivals with a show of huge power.

Boonen’s main sprinting rival, Robbie McEwen (Davitamon-Lotto), couldn’t keep up, then head-butted fellow Aussie Stuart O’Grady (Cofidis) while fighting for second place. The incident was a demonstration of the feistiness of the sport’s top sprinters, who pour all their aggression into 300 meters of drag racing; it also got McEwen relegated to last place on the stage for “dangerous tactics.”

Boonen now has a firm hold on the sprinters’ green jersey – leading O’Grady 70 points to 50. The polka-dot jersey worn by the leader of the mountains competition went to Erik Dekker (Rabobank) after the Dutchman led a trio of racers away from the pack 21 kilometers into yesterday’s stage.

Dekker, Rubens Bertogliati (Saunier Du val-Prodir), and Frenchman Nicolas Portal (AG2R) stayed away for close to 190 kilometers, but they never established a safe lead. With about five kilometers to go and the pack in sight, Bertogliati gave up, though Dekker and Portal keep attacking, hoping for a miracle.

Dekker won on these roads last year in the Paris-Tours classic in a similar fashion – a long break that held off the charging peloton at the line. He took that race by a single second, but he was not so lucky yesterday: The peloton swept up with about 2.5 kilometers left in the stage, setting the stage for the dramatic sprint that ended with Boonen’s arms raised in victory.

For the Tour’s top contenders, it was a day to relax before today’s team time trial. Armstrong re-established himself as the favorite with his virtuoso performance in Saturday’s first stage, a 19-kilometer time trial. His second-place finish was a reassuring sign from an athlete who has been less than convincing so far this season. Had his right foot not slipped out of its pedal in the charge from the start house, throwing off his pace for a few seconds, Armstrong might well have captured the 11th time trial of his Tour career.

Instead, the stage went to Zabriskie, who earned his place on CSC’s Tour team with his dominating performance in the time trials at the Giro d’Italia. Zabriskie’s performance on Saturday set a new Tour record for an individual time-trial record. His average speed of 54.676 km per hour broke the record set by Greg LeMond on the final stage of the 1989 Tour (when he took the yellow jersey from Laurent Fignon by five seconds).

The two other Americans whose fine weekend performances have them near the top of the standings are George Hincapie (Discovery), who sits 57 seconds back in fourth place, and Floyd Landis (Phonak) in sixth at 62 seconds. Hincapie has been Armstrong’s most loyal ally though all six Tour victories and will give his all for Armstrong. But Landis, after serving his apprenticeship under Armstrong, is now racing against his friend. At 29, he’s come to the Tour to see if he can contend for the overall title.

Still, none of the Americans are expected to be strong enough to overthrow Armstrong. That billing is reserved for Zabriskie’s CSC teammate Ivan Basso and the T-Mobile duo, Jan Ullrich and Alexandre Vinokourov; each is in striking distance after three stages. Vinokourov crossed less than a minute behind the Americans yesterday, and Ullrich, who crashed through the rear window of his team car in a practice run just the day before, managed to keep just 10 seconds between himself and the charging Kazakh.

Their eyes are all on today’s 67.5-kilometer team time trial. It is essential for CSC and T-Mobile to not lose much time to Armstrong’s well-drilled blue train. Time will be awarded based on the order in which the teams finish: The second-place team will lose 20 seconds, the third place will lose 30, the fourth will lose 40, with a maximum time loss of 3 minutes.