If the same nation's players happen to be facing off at the quarter or semi-final stages, it's quite common for the team bosses to ask the less-in-form player to make victory easier for the more-in-form player. Usually, this means shorter rallies... and also a couple of decisive 'errors' in the closing stages. This allows the winner to conserve quite a bit of energy for the later semi-final or final against a player from a rival nation. Inevitably, the player asked to 'give way' is going to be quite bitter about it (especially in a sport in which form is, at best, a fluctuating characteristic). But I'd imagine that the team bosses give this question a lot of thought before they make a final choice. And, yes, they still go wrong on occasion (e.g., Bao Chunlai instead of Lin Dan at the recent French Open). It'd be very unfortunate if personal likes and dislikes dictated any part of this 'tactical selection' of the one-with-the-best-chance-of-winning. From what I know of China, their 'ugly, unethical' but 'tactical' choice of a national Goliath is a careful and objective process.