Well, -sen is a marker for danish/norwegian names and -son for swedish/icelandic. Iirc, after the Nordic union was broken up in the 1300s sweden went back to the scandic roots in its language just to be different from the others - the same phenomenon can be seen in former yugoslavia for example, newish nationality - newish language.
Strange that this sen/son should be so difficult for foreigners, the suffixs O' & Mc/Mac fill the same function but those are seldom mistaken for each other - maybe it's exhaustion after reading more than two vowels for the english speaking or short attention span that don't last until the end of words?!
Anyway, enough about that - here's the draw for the first round:
28/4 Rond 1
Jan Timman - Emanuel Berg
Tiger Hillarp-Persson - Pontus Carlsson
Igor Khenkin - Alexei Federov
Suat Atalik - Daniel Stellwagen
Slavko Cicak - Jonny Hector