American midfielder Polvara was ruled out for five months with a hamstring injury which required surgery, but took on an alternative role during the period.
Pitching up at Pittodrie hoping to win a contract, these 25 trialists had a chance to sign for the Dons.
A ragged display v Hibs to lose for the third time in the Premiership this season laid bare Aberdeen's immaturity in defence, writes Willie Miller.
As well as the news on first-choice goalkeeper Mitov, Aberdeen have also been linked with a Latvia international defender.
The Dons visit Killie on Boxing Day - but you'll need the password in this article for your chance to win Dons Score Predictor League £££.
The Dons paid for individual mistakes against Hibs, but lambasting those individuals publicly or behind the scenes will only sow division, writes Duncan Shearer.
