Celtic have asked former manager Martin O'Neill to approve a five-month loan deal for Aston Villa defender Curtis Davies.
Davies, 24, is desperate for games after missing most of this season with a shoulder injury and sliding down the pecking order at Villa.
Celtic now hope to overcome O'Neill's doubts about allowing the former England Under-21 cap to spend the second half of the season in Glasgow.
Tony Mowbray sold the towering central defender to Villa from West Brom for £8million and must now await a decision from one of his predecessors and the player himself, while keeping a number of alternative irons in the fire.
The Parkhead side, who visit St Johnstone tomorrow, are also awaiting a final decision from Arsenal 's Philippe Senderos.
Arsene Wenger confirmed yesterday that Celtic remain an option for the Swiss central defender, despite demand for his services from Germany, Italy and England. Portsmouth's Marc Wilson has also been mentioned as a loan deal.
'I think there's still a few bits of business to be done,' said Mowbray. 'It's quite interesting there are one or two bits of business going on that you don't seem to have got a hold of. I'm sure it won't be long before those names get out.
'The bottom line is there are some that you know that could happen, and some you don't know.
'You never know because you are one phone call away from everything collapsing, or you try to take these things along a little bit at a time, hopefully to a positive conclusion. 'But there are a lot of people in the chain to make a deal happen and sometimes one of those people just blows it out of the water.
'The lure of Celtic still appears to be strong. The name of the club, the history, the fact they're in Europe is a draw. But the English Premier League is a huge draw for footballers, as well.'
Mowbray is set to clinch a deal for Danish striker Morten Rasmussen after agreeing a £1.5m fee with Brondby.
The Danish league's top scorer, Rasmussen has a colourful past, surviving a three-month suspended sentence for credit-card fraud to feed a gambling addiction last year.
Injury-prone in the past, the Dane is expected to arrive in Glasgow tomorrow and will undergo a medical on Monday before penning a three-and-a-half year contract worth a reputed £12,000 a week.
Rasmussen confirmed he has been speaking to his agent, Ivan Benes, in recent days, adding: 'Yes, I've heard a little, but mostly I've read about it through the media. It could, of course, be interesting - but until I know more, it's difficult to comment.'
Mowbray, meanwhile, has played down expectations that Rasmussen's arrival will seal the departure of Scott McDonald, currently sidelined by a hernia injury.
Sportsmail understands Middlesbrough are one of a number of clubs still weighing up a bid for the Australian. 'Watch this space,' said Mowbray, 'but I would suggest, at this moment, no.
'It's old news. Was Roberto Martinez not quoted as saying he was interested in McDonald?
'I'm interested in Lionel Messi. But I don't think there is a story there.'
Meanwhile, Celtic are set to conclude a pre-contract agreement for Motherwell's 18-year-old prospect Paul Slane to join in the summer.
Explore more:People:Martin O'Neill, Philippe Senderos, Lionel Messi, Roberto Martinez, Tony MowbrayPlaces:Glasgow, Italy, United Kingdom, Germany, EuropeOrganisations:English Premier League