The American is bidding over the next three weeks and 3,500 km to surpass fellow five-times winners, Jacques Anquetil, Bernard Hinault, Eddy Merckx and Miguel Indurain.
Even though Armstrong, German Jan Ullrich and American Tyler Hamilton could feature prominently in the 6.6-km
Liege is hosting the Tour for the 10th time and the race will stay in Belgium for three days before returning to France on Tuesday.