Celtic are holding talks with Jeonbuk Hyundai Motors technical director Ji-Sung Park in London, after making a bid of around £3m for striker Gue-Sung Cho.
It is understood the South Korea international is a player Rangers are also aware of but no official approach has been made for the player.
Bundesliga club Mainz made an offer similar to Celtic's, while Ferencvaros were also interested in the 24-year-old but have not tabled a bid as of yet.
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MLS side Minnesota United have confirmed to Sky Sports News that they are interested in Cho, with reports in South Korea suggesting the American club have put together a package that would eclipse any offers currently on the table for Cho.
Sky Sports News revealed Cho was a target for Celtic in December after he scored two goals against Ghana at the World Cup.
Celtic have been scouring the globe for talent recently, with scouts sent to countries including South Korea, Iran and the UAE. It is understood a number of targets from the Middle East and Asia have emerged.
Celtic open to Welsh offers
Stephen Welsh could however leave Parkhead this month, with Celtic willing to listen to offers for the defender.
The centre-back is attracting interest from clubs in Europe and the MLS.
It's believed boss Ange Postecoglou is a fan of the 22-year-old, but understands Welsh's needs and desires for regular football to progress in his career.
In the summer transfer window, Celtic knocked back a season-long loan bid, with an option-to-buy of £3.5m, from Toulouse, while also turning down an approach from Udinese for the Scotland under-21 international.
Rangers monitoring Cantwell
Rangers, meanwhile, are monitoring Norwich City's Todd Cantwell, who is out of contract in the summer, but are yet to make a formal approach for the midfielder.
Speaking to Sky Sports News, Ibrox boss Michael Beale confirmed he is hoping to add two or three players to his squad during this transfer window.
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"Our phone has not stopped," he said. "There are a lot of players interested in coming here. I have to make sure they are the right ones.
"I would say that the two or three I've spoken to are very keen to come and sooner rather than later, the same on our side. So let's see."
Follow the January transfer window with Sky Sports
Who will be on the move this winter? The January transfer window closes at midnight in Scotland on Tuesday January 31, 2023.
Keep up-to-date with all the latest transfer news and rumours in our dedicated Transfer Centre blog on Sky Sports' digital platforms. You can also catch up with the ins, outs and analysis on Sky Sports News.