Perhaps interestingly, back when I used to do a tiny little bit of prize fighting, the two worst losses I took were from those two exact techniques.
One guy threw so many leg kicks (as we called them in Canada at that time) into my left thigh that it just buckled partway through round maybe 4? and he crushed me with a knee on the way down and I came around in time to see him jumping triumphantly with both hands in the air while I tried to get to my feet and kept falling down.
The other guy hit me with a fairly straight descending left hand, just at the bottom of my ribs on my right side. I think I was trying to lay a hard right cross on him but I can't even really remember. I remember he leaned back and I saw his left pretty straight just gunning down into my side but I wasn't really expecting anything from it. I felt okay for a few seconds and then it was like the life just started draining out of me and I felt really confused. Also I thought I had taken a groin shot because that's where it felt like the pain started but I didn't. Anyway I stepped around awkwardly for a second or two and then fell down on the mat and I'm about 95% sure I started crying. It was the worst loss I ever had and easily the most painful.