When Lance Armstrong lays down the law in the Tour de France, other riders sometimes have no choice but to obey. Just ask Filippo Simeoni.

The Italian, who is involved in a legal battle with the five-time champion, tried to speed ahead of the pack Friday on the Tour's 18th stage. Armstrong's reaction was unequivocal: No way.

Even though Simeoni is way down in the overall standings and cannot threaten Armstrong's march to a record sixth Tour victory, the Texan chased after him.

Their animosity stems from Simeoni's testimony against sports doctor Michele Ferrari, with whom Armstrong has ties. Ferrari faces allegations of providing performance enhancers to riders and in 2002, Simeoni told an Italian court that Ferrari advised him to take drugs.

Ferrari has testified that he never prescribed or administered banned substances.

The result at this Tour is bad blood between Armstrong and Simeoni.

"All he wants to do is destroy cycling and destroy the sport that pays him, and that's wrong," the Texan said after his extraordinary move to rein in Simeoni.

The Italian was trying to catch a group of six riders who, in an effort to win, pulled away from the main pack early in the stage through eastern France.

Armstrong went tearing after him. When he and Simeoni caught the escape group, the riders there told Simeoni he was not welcome. They knew that their chances of winning the stage were nil if Armstrong stayed with them. Simeoni eventually demurred, breaking off his attack and returning to the main pack -- with Armstrong.

"Armstrong demonstrated to the entire world what type of person he is," Simeoni said. "It is not reasonable that a great champion doesn't give a chance to a small rider like me and the others. ... I suffered an injustice from him while everyone was watching."

Spain's Juan Miguel Mercado, who was part of the escape group Simeoni wanted to join, went on to win, beating fellow Spaniard Vicente Garcia Acosta in a sprint at the finish at Lons-Le-Saunier.

The stage win was 26-year-old Mercado's first in two Tours. He finished 36th last year.

He completed the 103.2 miles in 4 hours 4 minutes 3 seconds.

"It's a fantastic day," he said. "I had the good fortune of being in the right escape."

Armstrong's overall lead on Italian Ivan Basso remained unchanged at 4:09 -- more than enough to see him through to the finish in Paris. He will carry that advantage into the last big challenge of this Tour -- a time trial Saturday in Besancon, where Armstrong is again a favorite to win.

The next day, barring a major disaster, Armstrong will become the first six-time winner of the 101-year-old race. And the bad news for his rivals is that he's not done yet.

He said he will race another Tour, although maybe not next year. He is eager to try other events, including Classic races that are an important part of cycling tradition and which "require a different type of focus."

Armstrong has faced criticism within cycling for focusing too heavily on the Tour and ignoring other events.

"It's a special race. It's everything. You can't have this intensity in any other event," he said. "I'll do it again before I stop."

In a newspaper interview earlier in the Tour, Simeoni defended his testimony against Ferrari and said that Armstrong was giving him the cold shoulder. He also said Armstrong has called him a liar and because of that, he is suing him for libel.

"In the morning I look for him, I ride up to him, but he is cold, detached. He acts as if I don't exist," Simeoni told the French sports daily L'Equipe.

Sebastien Joly, a French rider who was in the escape group, said they asked Simeoni to leave them.

"When he let go, Lance had the kindness to do the same thing," he said. "I think it was a reaction of pride on Armstrong's part."

"It was bizarre, really strange," Mercado added.

"All he wants to do is destroy cycling and destroy the sport that pays him, and that's wrong," Tour leader Lance Armstrong said of Filippo Simeoni, with whom he has been feuding.Juan Miguel Mercado, 26, benefits from the battle between Lance Armstrong and Filippo Simeoni, winning the stage for his first victory in two tours. SIMEONI

"I suffered an injustice . . . while everyone was watching."