In terms of big to small, there are points, sets, matches, tournaments. There is nothing special about "matches", it is simply one of a hierachy of things. Arguably, the most special one should be "tournament", since it is the largest. Yet there is an arbitrary rule that you must try your best to win the individual matches, even if it means you are less likely to win the tournament. For example there is no rule against deliberately losing a set to win the match. Say you knew that your opponent had some serious mental choking issue, then you may decide to let them win the first set and thereby cause them to get very nervous and lose. There would be absolutely no problem with your cunning plan, nobody will come and kick you out of the tournament for "deliberately losing a set". Or perhaps you decide to use the first set to "feel them out", that is also perfectly acceptable. I would argue that if you knew that winning the match would decrease your chances of winning the tournament, then surely you should be punished for "not doing your best to win the tournament"!