I suppose one of the best matches I ever played was against a guy everyone considered a total noob, and he himself said that he was. We were playing a 1 shot kill instagib match in UT99 on a small, symmetrical level, 1v1. It was a tournament match and everyone was totally convinced I was gonna win outright and kick serious ass (because I used to be pretty good at it). In my cockiness I decided to play the game off my mattress, because I figured he'd never get an accurate shot in, giving me time to aim properly...
Imagine my surprise when he's absolutely dicking me over, winning the first match 30-18.
I was still playing off the mattress, but the next level was a huge map and distance based, which I excelled at, and beat him hands down, which meant the last map was the tie-breaker.
I actually moved into the other room for this, it was pretty exciting and we had gained the interest of a few spectators, wondering whether the lad was gonna properly beat me. The last map was another fairly small map, although there was still an element of being able to hide and use serious tactics, which I was taking full advantage of. As a player I'm fairly sneaky, and in 1 shot kill 1v1 matches, taking someone on head on is suicide unless you have lightning fast reflexes, and his aim was exceptionally good that day. The match began and he took the lead quite early by about 10 kills, and I was absolutely bricking it, for every kill I got, he seemed to get 2. I managed to pull it level and the score was 29-29... And the final kill seemed to take forever, neither of us could hit the other, and we ended up ducking behind cover. In almost a movie style, we leapt out at the same time using the leap function and I'm lucky enough to get the shot in first.
People almost wanted the other guy to win, because I'd gained a reputation and was at the time the joint leader of the clan. Turns out it wasn't actually him playing at all, but someone completely different who had been playing since the game had come out :O So basically the guy tried to cheat me out of it without using aimbots, and failed ^.^