Marcus Rashford and Antony were allowed to go out on loan in the January transfer window.
Their problems have gone from bad to worse after Kobbie Mainoo was ruled out for weeks with a worrying injury, and Ugarte and Collyer were also sidelined.
Amorim has Christian Eriksen and Casemiro as options to play in midfield at Spurs, and teenager Jack Moorhouse is among a number of academy players who have travelled to London along with Chido Obi-Martin, Sekou Kone, Harry Amass and Elyh Harrison.
United usually make the journey by rail, but had to take the team bus due to train cancellations as their preparations for the game were further disrupted.