The Elland Road club are understood to have applied for special dispensation to make a short-term signing outside the window.
West Bromwich Albion’s Jonathan Bond is one of those believed to be on United’s radar as the clock ticks down towards tomorrow’s Championship clash with Bristol City.
Tom Heaton, Burnley’s England international, is another to have been linked with Leeds in recent days.
Pontus Jansson is also expected to miss the game with the Robins through injury, but it is the loss of both Peacock-Farrell and Blackman inside the space of a week that is most focusing minds at the club’s Thorp Arch training ground.
Blackman suffered a broken leg when playing for the Under-23s last Friday and has since returned to parent club Chelsea.
Head coach Marcelo Bielsa said: “For Peacock-Farrell it will be difficult because at the end of the training session (on Wednesday) he had a problem in his knee. He won’t be able to play.”
As happened with Barnsley recently, any club without a senior goalkeeper available can be granted permission by the Football Association and Football league to make a short-term signing. Any new face would have to be signed by noon to face the Robins.
The double injury blow leaves United with just Academy goalkeepers Will Huffer and Kamil Miazek, on their books.
Huffer, an England Under-20 international, has never played at senior level, while one-time Feyenoord youngster Miazek made four appearances on loan at Polish club Chojniczanka Chojnice a couple of years ago.
Centre-back Jansson suffered a foot injury in the 4-1 defeat at West Brom on November 10. He subsequently pulled out of the Swedish squad to face Turkey and Russia in a UEFA Nations League double-header.
He joins Luke Ayling and Gaetano Berardi on the sidelines, leaving Liam Cooper as the club’s only recognised fit senior centre-half.
Kalvin Phillips is expected to drop back into the defence tomorrow against Lee Johnson’s Bristol City side.