2000 Audi A4 Quattro 2.8L

The lowbeam headlight stopped working, first on the driver side and subsequently after a few days on the passenger side as well. The high beam works fine. The low beam is not working.

I checked the bulbs, they look fine. i.e. the filament is not broken. I checked the fuse and found that fuse #20 for passenger side was blown. I promptly replaced the fuse, but as soon as I turned on the headlights on low beam, I could hear the fuse blow up. The passenger side low beam fuse blows up as soon as I start the headlights after replacing. The driver side fuse #21 is not blown.

Any ideas on what I should be looking at next?

Thanks.