It is likely that whoever steps in to fill Arsene Wenger's shoes for the top job at Arsenal will have limited funds to sign players, making Freiburg's £35million asking price for Soyuncu a concern.
Papastathopoulos would cost almost half of that, at £17.5million, and is already known to Arsenal's head of recruitment, Sven Mislintat, with whom he spent time with during their Dortmund days.
The Gunners are in need of a centre-back, having lost Laurent Koscielny out to injury for six months and Per Mertesacker having retired from his professional playing career.