Chelsea reportedly sent a scout to watch Marseille defender Boubacar Kamara in action during his team's 2-1 win over Dijon in Ligue 1 on Friday night.
Kamara, 19, is currently in his first full season with Marseille's senior team and has already made 19 Ligue 1 appearances during the 2018-19 campaign.
According to Mercato365, Chelsea had a representative in the crowd to watch Kamara in action against Dijon, with the teenager playing the full 90 minutes in central defence.
Kamara, who has also previously been linked with AC Milan and Arsenal, only has 18 months left to run on his current deal with Marseille.
Senior Chelsea centre-backs Gary Cahill and David Luiz will both see their contracts with the Blues expire at the end of the current season.