Унион Ла-Калера
On 4 January 2018, Fernández was loaned from Racing Club to newly-promoted Chilean Primera División club Unión La Calera with an option to buy. The 23 year-old scored 11 goals in 12 league matches for Unión La Calera, helping to deliver one of the best seasons in the club's history. His final match for the club was on 29 May against Colo-Colo, in which he scored in the 2–0 victory. Unión La Calera were 3rd place in the league at the time of Fernández's departure to Mexico.