AC Milan have announced they are negotiating the sale of Brazilian forward Robinho to new MLS franchise Orlando City.
Ronald Koeman says Southampton will continue to move forward even if they lose another key player in Dejan Lovren.
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.