When you clearly see that a ball was in, and your opponent calls it out from an extremely untenable position (completely across the court, where they have no business making a close call; while you are right on top of the ball, down the line from it in fact - and it absolutely hit smack on the line) - what do you do? Politely ask to see a mark (on clay)? Knowing that the mark indicated will not be the right one, regardless... Just give up the point, knowing 100% you just got hooked, and try not to let it bother you. Tell the opponent you disagree, but will allow the call to stand, per the rules. I've got news for you - until we all have "shot spot" or "hawkeye" installed on our courts, this discussion will never end. The end of this scenario never varies, unless you happen to be playing an exceptional "sport". If you question a call for any reason - you will be perceived to call your opponent a LIAR. Where the h-ll does that come from? None of us is perfect at making calls. Many times I prefer to play the point over, if my friendly opponent vehemently disagrees with a call I made. But I would never assume they are "calling me a liar". Today, as you can guess, I played in just such a match. I hit a ball that my partner and I saw clearly on the line, but was called out by one opponent, who was completely across the court from it and could not have possibly properly made the call. Her partner just shrugged his shoulders and said "I dunno, didn't see it". My partner and I responded calmly, "whatever, it's your call. We thought it was good but we accept your call." The female opponent, however, went absolutely BALLISTIC, ranting and raving on and on about how we were calling her a LIAR, and we should know her better than that, and it's her call, and we have no right to challenge her call, and so on. Fact is, we weren't challenging her call, no matter that it was marginal; and nobody called anybody a liar! She let this get to her so much that she started playing like cr*p, and lost the match. Afterwards, she stomped off the court, refusing to shake hands - while the rest of us hung out together, having a cold drink and making match plans. I don't feel like it's wrong to verbally, politely disagree on a call, do you? As long as it's done in a civil and non-accusatory manner, I feel better about saying what I'm feeling, and not holding it in. The call doesn't have to be reversed, we don't have to play it over - I readily accept the call - but I don't have to agree with it, because I simply didn't believe it. Should I pretend that I have changed my mind about this errant call? To me - there is no reason to get emotional over anything on court - just not worth it, in any way. While the rest of us "moved on", this person lost the set because her ego and insecurity got in the way.