CYCLING/Tour de France: Lance Armstrong spent yesterday's rest from Tour de France action looking forward to what he described as the "most important time trial of my life".

That happens tomorrow following today's stage from Narbonne to Toulouse and Armstrong said: "I have already reconnoitred the time-trial course, but I will do so again on the morning of the race."

Armstrong is taking no chances after his slip-up in the prologue time trial at the start of the race when he decided against inspecting the course and produced a disappointing performance.

"It will be the most important time-trial of my life," he added, "but in the meantime I will be spending time with my family in Narbonne."

While Armstrong, the four-times Tour winner, is the man in possession of the leader's yellow jersey, Germany's Jan Ullrich, who won the 1997 Tour and is in sixth place in the standings, two minutes and 10 seconds adrift, believes he can haul the American in. Ullrich reckons Armstrong may be vulnerable to an attack in the Pyrenees and said there was a chance he could win his first stage of cycling's premier race in five years in the mountains of south west France.

"If I'm on good form and I'm feeling good on the day, then it might be possible," he said. "The Pyrenees this year are tougher than the Alps and a lot can happen there."

Ullrich is also looking forward to tomorrow's 47km individual time-trial to improve his overall position before the Pyrenees.

"I hope I can gain time on some of the mountain specialists and get a morale boost for the stages in the Pyrenees," said the 29-year-old.

Ullrich, who was second behind Armstrong in 2000 and 2001, thinks the American has never been in a trickier position going into the second half of the Tour.

"Lance had certainly expected to be in a better position at this stage," he said. "In the last few years you never saw his main rivals just a few seconds behind him after the first mountain stages."

Armstrong admits the blazing heat on this year's Tour has made it as tough as any he has competed in. "It has been really hot for several days," he said. "I have never known so many days like this in a row on the Tour. I am trying to drink lots of water - even to over-hydrate myself. But I will still train on the rest day."

Armstrong leads the second-placed Kazakh Alexander Vinokourov by a mere 21 seconds.