Mali international centre-back Boubakar Kouyate is wanted by French Ligue 1 side Metz amid a £1.4m price slide that could reignite interest in the stopper.
Both the Hoops and rivals Rangers have previously been linked with a £4.5m deal for the 23-year-old Troyes defender.
But while the Ibrox men signed Leon Balogun from Wigan, Celtic are still looking for a replacement for the departed Jozo Simunovic.
The 23-year-old impressed as his club narrowly missed out on promotion to Ligue 1 last term.
They finished just three points behind champions Lorient, with the season ended early due to the pandemic.
Lens seemed in poll position to sign the star, with Schalke 04 and Eintracht Frankfurt also interested but an offer fell short of the valuation put on Kouyate.
Troyes were hoping to use the competition to push the transfer fee to around £4.5m with Kouyate under contract until 2022 but Metz are only prepared to offer £3.1m, according to France Football.
And should the Ligue 2 side now accept this lower offer, the Celtic management team could spy a bargain.
The Hoops already have a large French speaking contingent in their squad including Christopher Jullien, Olivier Ntcham and Odsonne Edouard
The centre-back previously played for Sporting's B team alongside former Dundee United creative midfielder Ryan Gauld.
He was named on the bench in L'Équipe's Ligue 2 team of the season and despite playing in defence he finished as Troyes' top-scorer with six goals in 18 games.
