Nottingham Forest boss Stuart Pearce has no intention of sending fit-again striker Dexter Blackstock out on loan.
Bryan Ruiz found himself frozen out at Fulham under Felix Magath, but will be offered a clean slate by Kit Symons.
Newspaper reports suggested United boss Sir Alex Ferguson held talks with the player in London on Sunday over a switch that could be worth up to £15m.
But Palace have told Sky Sports they have not given Zaha permission to talk with the Premier League leaders and no deal has yet been struck.
Arsenal and Tottenham are among others said to have been tracking the 20-year-old's progress, although United remain favourites to land him.