"We've send the fax to the UCI this afternoon," said Jose Maria Buxeda, one of Landis's two Spanish lawyers. "Now we'll have to adjust to their calendar."
The UCI is the Swiss-based international cycling union.
Buxeda said he's not sure when the "B" test will be carried out at the Paris doping laboratory, though it could be sometime this week.
Landis, who has returned to the United States, is willing to attend the analysis depending on the date, Buxeda said.
Landis tested positive for elevated testosterone levels following the 17th stage of the Tour de France, where he made a stunning solo breakaway in the Alps to put himself back into contention for victory after a poor performance the previous day.
If his the B test is negative, Landis would be cleared. If it's positive, the 30-year-old American would face formal doping charges and could be stripped of his Tour victory and banned for two years.
Landis's lawyers say they fully expect the backup test to confirm the original finding.
Landis, speaking in Madrid on Friday, said his test results had nothing to do with doping, and that the high level of testosterone in his body was the result of his natural physiology.
Testosterone is a naturally occurring male hormone that is banned when it is found in a ratio greater than 4:1 to another hormone, epitestosterone.
Former professional Spanish cyclist Jesus Manzano said he was given testosterone when he competed for the Kelme team, and immediately felt its effects.
"It gives you a lot of strength, and it works very well," he wrote in the Spanish sports daily AS on Saturday. "It produces a euphoria."
Oscar Pereiro of Spain, who finished second overall in the Tour de France, would be declared the winner if Landis loses the Tour de France title.
It would be the first time in the history of the Tour of France that the winner has been disqualified for doping.