In May 2016, Frank de Boer announced that after 6 years and four domestic league titles, he would be leaving the club. Later in the month, it was announced that former Feyenoord technical director and player, Peter Bosz, would take over the side. After initially losing 5–2 on aggregate to Russian side FC Rostov in the Champions League qualifiers, Ajax would go on to play in the 2017 UEFA Europa League Final, their first European final in 21 years. They would lose the match 2–0 to Manchester United, whilst fielding with the youngest side ever in a European final, averaging an age of 22 years and 282 days. For the third consecutive season, they finished runner-up in the Eredivisie, this time to Feyenoord.