Fernando Torres is returning to Atletico Madrid on loan until the end of the 2015-16 season.
Steve Clarke is hoping to keep Glenn Murray at Reading after his loan deal expired following the 2-1 win over Norwich.
Aberdeen have been handed a triple boost with the news Jamie Langfield, Jonny Hayes and Peter Pawlett have all signed new deals.
Goalkeeper Langfield and striker Hayes have penned contract extensions that keep them at Pittodrie until the summer of 2016, while midfielder Pawlett has committed himself until 2017.
Dons boss Derek McInnes says the signings are a major fillip ahead of Saturday's meeting with Celtic and expects all three to have a key role to play this season.
He told the club's official website: "These lads want to win something with Aberdeen, make no mistake about that, and they did not take too much persuading to continue their careers here.
"All three are very important players for this club and will have significant roles to perform in the months ahead.
"As I have continually said, we have made a decent start to this season but are far from the finished article.
"However, it is important to ensure you keep your best players and knowing Jamie, Jonny and Peter have committed to the long term, enables us to have a continuity going forward and, in the short term, gives everyone a lift ahead of the weekend trip to Celtic."