Here, we take a look at Kristensen's career so far:
1. January 2015
Kristensen makes his international debut for Denmark Under 18s. Photo: Valerio Pennicino
2. January 2016
Kristensen signs his first professional contract at FC Midtjylland, the Danish Superliga side where he has been training since he was 15 years old. He makes his senior debut from the bench in a 2-1 defeat to FC Nordsjælland in March 2016. Photo: Andreas Hillgreen
3. January 2018
Kristensen joins Ajax on a four-and-a-half-year contract and the defender makes eight Eredivisie appearances in the second half of the 2018/2019 season. Photo: Dean Mouhtaropoulos
4. May 2019
Kristensen scores his only goal of the season in Ajax's 4-0 victory in the KNVB Cup final against Willem II. Photo: Dean Mouhtaropoulos
5. May 2019
Ajax steamroller European giants Real Madrid and Juventus to reach Champions League semi-final against Tottenham Hotspur. Kristensen's involvement in the Dutch side's impressive run is limited to an eight-minute bench appearance in a Group E clash against AEK Athens. Photo: John Thys
6. May 2019
Kristensen celebrates with Matthijs de Ligt during his final game for Ajax, a 4-1 Eredivisie win over De Graafschap. Photo: Dean Mouhtaropoulos