Aaron Ramsey is in Glasgow for a medical to join Rangers on loan from Juventus.
The Wales midfielder, 31, has been in talks with the Scottish Premiership leaders, who visit Celtic on Wednesday.
Ramsey has not appeared for Juve since making a substitute appearance in the Champions League in October.
Meanwhile, Rangers have signed Mateusz Zukowski from Lechia Gdansk for an undisclosed fee, subject to international clearance.
Zukowski's arrival on a three-and-a-half-year contract comes four weeks on from fellow right-back Nathan Patterson's £12m move to Everton.
Winger Amad Diallo joined Rangers on loan from Manchester United last week, scoring on his debut in Saturday's 3-3 draw with Ross County, and James Sands arrived on an 18-month loan from New York City, with a view to a permanent move.
Rangers manager Giovanni van Bronckhorst has lost midfielder Ianis Hagi to injury for the rest of the season. Jermain Defoe departed, with fellow striker Cedric Itten recalled from a loan at Greuther Furth.