Ullrich, Armstrong and the other 149 survivors of a peloton that numbered 198 at the start of the race were yesterday enjoying their second and final rest day as they were transported to Pau where today's final mountain stage gets underway.
The momentum is back in favour of the 31-year-old Texan whose brilliant victory at Luz-Lardiden in Monday's 15th stage has given him a 1min 07sec advantage over the 29-year-old from Rostock in the former East Germany.
Armstrong had started the day just 15 seconds ahead of Ullrich and 18 ahead of Alexander Vinokourov of Kazakhstan but by the end of the stage had eclipsed both men with the Kazakh rider now 2:45 adrift and needing to produce something extraordinary if he is to prevail.
However, Ullrich believes that, unless the Texan can extend his lead, that 1:07 might not be enough ahead of Saturday 's time-trial on the penultimate day of the race.
"The Tour is not over yet," said Ullrich who in addition to his Tour win in 1997 when Armstrong was fighting for his life against the ravages of cancer has also finished runner-up four times, twice to the Texan and once apiece to Denmark's Bjarne Riis (1996) and Marco Pantani of Italy (1998).
"Lance is certainly worried that his lead is not big enough. I really fought today but it was not enough. However, on previous Tours on mountain stages Lance has taken two minutes off me and this time I only conceded one which is not so bad. I am just disappointed I did not come second and get more bonus points."
Ullrich finished third in the 15th stage behind the Texan and second-placed Iban Mayo of Spain. The German had no regrets over not taking advantage of Armstrong's fall when he collided with a spectator as he stuck to the peloton's code of honour which allows a rider time to re-join the race after a fall.
"I have never attacked someone who has fallen," said Ullrich. "I must think about the final mountain stage and then the time-trial and I am very confident about that."