Southampton are confident Jay Rodriguez will commit to a new long-term deal but the player will consider his options.
Wolfsburg director of sport Klaus Allofs says the club are keen to hold on to both Bas Dost and Nicklas Bendtner.
The Blanquillos finished rock bottom of the Primera Division - albeit just three points adrift of 17th-placed Celta de Vigo - with previous boss Manolo Jimenez paying the price for the setback earlier this week.
Zaragoza have turned to former Liverpool assistant Herrera, who has managed a host of Segunda Division sides in the past, to guide them back into into the top flight.
The 59-year-old has signed a two-year deal.