Celtic were expected to unveil new signing Kris Commons today after the Scotland winger finalised his move to Parkhead last night.
Commons is understood to have agreed a three-and-a-half year contract after Celtic beat Rangers to his signature.
Rangers moved for the 27-year-old earlier in the week but were soon put off by his wage demands with Celtic quickly stepping in.
Commons was out of contract at Pride Park in the summer and had failed to sign a new deal despite lengthy negotiations.
Celtic are believed to have succeeded with a bid of around £300,000 and Commons will now join former Nottingham Forest team-mate Neil Lennon's squad ahead of tomorrow's Scottish League Cup semi-final against Aberdeen.
Charlie Mulgrew faces his former Pittodrie team-mates following a successful return to central defence in Wednesday's 4-0 victory over Hearts.
Mulgrew was drafted in amid injuries to Daniel Majstorovic and Glenn Loovens but had little problem coping alongside Thomas Rogne.
The former Wolves player featured at centre-back on many occasions for Aberdeen and is happy to continue at Hampden.
"You feel a certain amount of pressure but you feel that in every game," Mulgrew said. "I played in the centre a lot last year and I have played there before so it was just like any other game.
"Thomas is a great player and the two of us were talking to each other, as were the full-backs, and all round it was a great team performance.
"We went out there to work hard and press from the front and the boys in front of us were great, they made our job easier and in the end it was a great result."