Celtic have confirmed that Rubin Kazan winger Wakaso Mubarak is undergoing a medical in Russia ahead of a possible loan switch to Glasgow.
However, the Ghana international was unlikely to be registered with UEFA by 23.00 on Tuesday night and would therefore be ineligible to feature against Maribor in the Champions League play-off first leg in Slovenia on Wednesday.
Celtic manager Ronny Deila said: "It is going on but it doesn't seem like there is going to be anything today. It is hard to get the paperwork together.
"I am not 100 per cent sure but I think it is going to be hard to have him ready for the game against Maribor."
The Hoops have been busy in the last week strengthening their squad, adding Manchester City's Jason Denayer and Aleksandar Tonev from Aston Villa on season-long loan deals.
Mubarak has won 19 caps for thje Black Stars, scoring seven times and would also be signing a season-long deal.
He played for Ghana against Germany and Portugal at the World Cup finals in Brazil during the summer.
The 22-year-old played in Spain for both Villarreal and Espanyol prior to his move to Russia last year.
You can see the game between Maribor and Celtic live on Sky Sports 5 on Wednesday night from 7pm