Never assume the old chain on any bike is the correct length. At our shop, if we had done this, there would have been untold catastrophes where rear derailleurs get torn off of the frame.
Wrap the new chain on the big chainring and the biggest cassette cog without going through the derailleurs. It has to be long enough to cover this combination, plus one inch (2 links) minimum. Some home hobby customers come in with triple cranksets and a retrofitted pie-plate rear cassette, resulting in no chain that will fit. The chain is too long in the small cogs, and it drags on the ground. The chain is too short in the big cogs, and they protest that: "I never use this gear combination". But inevitably they will, leading potentially to hundreds of dollars of damage.
BTW: Dura-Ace and XTR chains are massively counterfeited; assume every one of these you buy online overseas at a discount is a substandard fake. Buyer beware.