Nemesamt fight in Zerstörer - how to beat it?

First, a major kudos to the guys behind Quaddicted. It’s an awesome resource.

I’m replaying Quake and some of my favorite SP maps after a hiatus of several years. One of those favorites being Zerstörer, but I’m stuck in the Among the Dead map, specifically the part when you face your first Nemesant in small, locked room. I just don’t stand a chance against it - and I have no room to manoeuvre in either. Am I missing some kind of trick you should use to beat it?

OK, so I managed the fight by circle strafing like crazy. The Nemesant turned out to be rather squishy. Annoyingly, my char died a couple of seconds later after falling through the collapsing floor. And the rest of the map was also annoying. In short, a frustrating ending to that particular Zerstörer map IMO.