The club failed in a deal to sign the Leicester City goalie last summer.
Zieler conceded Leicester City's first Champions League goal at the fifth time of asking.
The Republic of Ireland international has been linked with a move away from Hillsborough.
The stopper was on loan at Bristol City this season after struggling for first-team football with The Foxes.
Nottingham Forest boss Dougie Freedman is hopeful over signing Michael Frey, but not getting ahead of himself.
After being announced as a Nottingham Forest signing, Ben Hamer has agreed to move to Bristol City.
Nottingham Forest goalkeeper Ben Hamer has played down the significance of him not having played a great deal of pre-season football.
Nottingham Forest goalkeeper Ben Hamer has explained that the entire squad buys into the vision of manager Dougie Freedman.
Nottingham Forest loanee Ben Hamer has revealed he's been given no assurances over his role by Dougie Freedman.
Leicester City's squad members have been laughing at Chris Wood's celebration for the development side.