Sergio Herrera, a 33-year-old Spanish goalkeeper, is a candidate for the goalkeeper position at Olympiacos, which is seeking to replace the departing Konstantinos Tzolakis. However, his transfer is considered very difficult to progress, as Osasuna is thought to be unlikely to agree to his departure. The effort to acquire another target, Stefan Ortega, is also judged to be very challenging. Herrera has been with Osasuna since July 2017 and his contract is valid until June 2028. His current market value is €2.80m, according to Transfermarkt.