Honestly, ive had tons of these moments in tons of video games haha.
To start off, in MW2 i just barely dodged a big shot of a AC-130 while capturing a flag in Domination. It was kinda frightening when suddenly a shot passes you and the sound on my TV was just waaaay too loud, but nonetheless i was just lucky and that flag made us win the game.
Secondly i have had dozens of lucky moments in StarCraft II, one of them being the most luckiest victory you could ever get. We both had one unit left: I had a Protoss Stalker and he had a Zerg Ultralisk. Well, that seems like i just lost instantly cause no way a single Stalker can kill a Ultralisk, yet you can out-micro it, which was exactly what i did and it kept going on, the guy raging at me for not giving up and then finally his Ultralisk died.