I beat one of the top ranked pro players once, in Quake 1 deathmatch. Felt pretty pleased about the win but how I did it is the thing that I feel proud of: I tried to avoid him, an unusual tactic in deathmatch. Map control, timing of items, routes, I couldn't compete there and I not only knew it I got to experience it firsthand. Chaos, coming from weird angles, unpredictable situations and tactics there can be no trained response to, that's where I was good and only under those conditions could I ever hope to beat him. So I actually managed to suck him into my world of bullshit and eeked out the win. Maybe he had a bad day, I don't know, but he was really good to the point that within the first minute I realized that oh, this is something completely different.
CTF was what I played most of the time because the grappling hook and runes was a natural fit for my play style, combined with the asymmetrical nature of the (sometimes huge) maps DOING WEIRD SHIT was a legitimate and often successful tactic.