Celtic are today finalising the signing of David Turnbull and hope to complete three more signings over the next week, Football Insider understands.
The Scottish champions have embarked on a major recruitment drive as Neil Lennon looks to strengthen in key areas of his team as well as build for the future.
A Celtic source has told Football Insider that a £2.75million deal rising to £3.25m with add-ons will be finalised imminently for Turnbull as long as scans on his knee get the green light from medics.
Progress is also being made on a loan deal for Brighton centre-back Shane Duffy and the permanent capture of Hearts left-back Aaron Hickey.
Celtic are also hopeful of signing another youngster who will go into their youth team set-up.
Turnbull is first expected to become their third permanent signing of the summer transfer window following the captures of Greek international goalkeeper Vasilis Barkas and Swiss striker Albian Ajeti.