Bayer Leverkusen are reportedly in talks to sign Celtic defender Kristoffer Ajer in this summer's transfer window.
The 23-year-old has just one year remaining on his contract and has suggested that a move away from Parkhead 'should happen'.
According to Sky Sports News, Leverkusen are in negotiations with Celtic over a potential deal for Ajer, while Premier League duo Newcastle United and Norwich City are also monitoring the situation.
The report also states that Serie A outfit AC Milan were interested in the Norwegian, but have since turned their attention to the permanent signing of Fikayo Tomori from Chelsea, who was on loan with the Italian club for the second half of last season.
A potential move for Ajer to Leverkusen could see Celtic sell another player to the Bundesliga club, after full-back Jeremie Frimpong joined in January, a transfer that frustrated former boss Neil Lennon.
Ajer has made 176 appearances for Celtic since joining the club in 2016, winning three Premiership titles, three League Cups and two Scottish Cups.