This is all you have to do - duck and punch. If Geralt's opponent begins his attack Geralt has to punch and attacks immediately after.

In many cases it's even easier: Look at the cursor. If it transforms in a point then hit:

https://www.youtube.com/watch?v=oO3P_YmKkho

I had some difficult with the fights too, and I don't remember very well how it can be done, but if you pay attention to the animation of your adversary, you can use a timing of duck and punch (sometimes it can interrupt your adversary's attack before he can hit you and even lock him in a sequence of well timed punches). You can try to movement arround, however be careful to don't get out of the area of the fight or you can lose (can happen with your adversary too). Maybe you can try some potions too (it works?).

Edit: looking at the video above, I is almost how I did it, but I didn't used the setting showed the pointer.

P.S.: the timing is the key in a real fight, right? So I don't think that it is a cheat.

Thanks, really good advice. Though I'd (eventually) figured out most of it, the positioning of the cursor is something I hadn't considered.

I may be having a Homer Simpson moment to be honest. There seem to be a lot of exp points for fighting.

Just been in and tried again, using the methods suggested.

I get plenty of good swings but Fat Fred dodges every time so I miss and make no impression on him at all. His Vitality is untouched while mine slowing goes down to defeat.

I move toward him but that has no effect other than getting me his.

I have tried fighting Eskel and managed to defeat him.

I have done a restart of the entire game. This is my (?) third time playing.

I'm sure there isn't any fault with the program it must be entirely me. Perhaps I'm intimidated by the opponent. He seems a decent enough fellow but his personal hygiene doesn't look too good.

C'est la vie. Though I was looking forward to defeating that fellow Vizima Jail.

If anyone has any idea what I'm doing wrong it would be great.

Hmh.

Same tactic. If he attacks, Geralt ducks (Press and hold RMB). As soon as the chunk finishes his attack Geralt himself hits the chunk - and ducks again. Rinse and repeat:

https://www.youtube.com/watch?v=k0CHuKuDsjY

(DL: hard)

Forget ducking. Just click a half second after your oppenent starts to swing and he will interrupt their swing with a fist to the face every time. At least if you have the fist fighting character powerups.

A lazy, stupid way that's working for me at the lower levels (Velen) so far, where I'm at level 13, is just dancing quickly back and forth between Fast & Parry (i.e, just quickly mouse: left, right, left, right, ...)

I I have played through all chapters several times and have beaten every fighter in the game using this method.