Tottenham have omitted Gedson Fernandes and Paulo Gazzaniga from their Europa League squad.
Spurs have 19 non-homegrown players, which is two more than Uefa's allowance for European competitions.
Spurs will face Austrian side LASK, Royal Antwerp, of Belgium, and Bulgaria’s Ludogorets in the group stage.
The summer signing of Joe Hart has bolstered Mourinho’s ranks of homegrown players and left Gazzaniga as the club’s third-choice goalkeeper.
The Argentina international was offered to Liverpool and Everton on deadline day, but the Toffees opted to sign Robin Olsen on loan from Roma instead.
Mourinho is set to use Alfie Whiteman, 22, or England Under-21 international Brandon Austin as his third-choice goalkeeper in Europe.
Gedson, 21, was Mourinho’s first Spurs signing, on an 18-month loan from Benfica, in January, but the midfielder has made just three starts. Spurs have the option to make his deal permanent next summer for a reported £56million.
Spurs’s situation is complicated because England’s Eric Dier and Wales defender Ben Davies do not count as homegrown. Dier came through Sporting Lisbon’s academy, while Davies came through the Welsh system.
Arsenal also have 19 non-homegrown players, with Mesut Ozil, Sokratis, the injured Gabriel Martinelli and William Saliba all left out of Mikel Arteta's Europa League squad.
