Rangers are considering a move for South African centre-back Olwethu Makhanya.
The 22-year-old Philadelphia Union star is on the club's shortlist as they look to bolster their defence for the upcoming 2026/27 season.
He has made more than 50 appearances in the MLS and was part of South Africa's World Cup squad this summer.
Rangers are continuing their pre-season preparations in Spain, with manager Derek McInnes admitting they still have "quite a bit of work to do" in the transfer window.
A right-winger, centre-back, and midfielder remain priority positions for the club, with Makhanya fitting the profile as a left-sided central defender.
This would allow Manny Fernandez to play on the right if needed, providing McInnes with more options in defence.
Rangers currently have Ross McCrorie and Dujon Sterling who can play at right-back, while Tuur Rommens is the first choice on the left.
However, they are considering a versatile option who can cover both sides, whilst allowing promising 16-year-old Ashton Scally a pathway into the first team.
Clinton Nsiala, who has featured in pre-season, is expected to move on to play regular football elsewhere.
The club has also decided to allow Danilo and John Souttar to leave Ibrox this summer, with talks regarding their exits ongoing.
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Danilo has attracted interest from clubs in South America, the Netherlands, and Cyprus, while Souttar is wanted by more than one English club, including Leicester City.
In midfield, Rangers are in talks over potential deals for Vajna Dragojevic and Jens Hjerto-Dahl, although any movement will depend on outgoings.
Nico Raskin has attracted interest, Connor Barron's future is uncertain, and Mo Diomande is in the final two years of his deal.
The signing of Cammy Devlin over the weekend took Rangers' list of central midfielders to six players.
Ivor Pandur, the club's new Croatian No.1, will join up with the squad on Monday after his break following the World Cup.
Devlin isn't at the camp in Spain either, having been given time off after his involvement with Australia at the tournament.
As exclusively revealed by the Rangers Review last month, Curtis has been offered a new contract by Rangers after his breakthrough season, with optimism that the Scotland international will agree to fresh terms at Ibrox.
Speaking in midweek, he said: "I did push for a loan, I think it was the best thing for me.
"I think it is one of those ones where if you go and do really well, it will stand you in good stead.
"I'm really happy to be back at Rangers now. I want to showcase my talent here, in Europe and the biggest stage."
Another young player who could soon be offered fresh terms is Rydnn McGuire.
The highly-rated 17-year-old, who has started all three friendly games so far in pre-season, is entering the final year of his deal, with further talks planned in relation to extending that contract.
McGuire has attracted consistent interest from England over the past year, with only 10 months on his current deal not stopping enquiries being made.
The club is aiming to appoint a permanent replacement for Scott Fry to handle set-piece responsibilities.
McInnes worked effectively with set-piece coach Ross Grant, now at Celtic, last season.
