Celtic are working intently on signing a marquee centre-back and want a deal done in the next week, Football Insider understands.
The Hoops are short of cover in central defence after allowing Jozo Simunovic to leave when his contract expired at the end of May.
A Celtic source has told Football Insider that Neil Lennon has made it clear to the hierarchy he wants another senior and proven defender to strengthen his back line.
However, the new arrival is set to be a loan move only rather than a permanent deal.
Preliminary talks have been held been Brighton’s Shane Duffy but Celtic face significant competition for his signature from Premier League clubs.
West Ham, Sheffield United and newly-promoted West Brom are all keen on the Republic of Ireland 28-year-old.