that is completely wrong, the A350 is in no way suppose to compete with the 777.
First Airbus said that everyone wants these massive planes and that there is no market for the 787, then Boeing started getting a bunch of orders for it and a lot of interest from airlines and Airbus realized they better try and get something on the drawing board so along comes the A350 which hasn't been a real barn burner so far. The A350 is meant to compete with the 787 as a 767/A300 310 size replacement.
I really have a hard time believing that all these airlines (some with fleets heavily weighted to Airbus) are picking 777 soley for better fuel economy. I know for a fact (and backed by Air France CEO's statement) that the 777 has much better dispatch reliability than the A340, in fact I would say it would be a fair statement to say the 777 has one of the highest if not the highest dispatch reliability of any aircraft. I know it is the most reliable aircraft at American.