The 24-year-old has been left out of the last two Tottenham squads in victories over Lokomotiv Plovdiv and Southampton.
Following Tottenham's 5-2 win over Southampton on Sunday, Mourinho put Alli's omission down to having too many players to pick.
He said: "At this moment, we have too many players in the squad.
"I had on the bench; [Steven] Bergwijn, [Giovani] Lo Celso, [Moussa] Sissoko, [Erik] Lamela… to have Dele, I need to leave somebody else behind.
"And that's the situation at this moment. He will play on Tuesday [against Leyton Orient in the Carabao Cup], he needs to show how good he is."
Subsequently, Bent, who spent two years at Tottenham from 2007, has rubbished Mourinho's reasoning and branded Alli's exclusion 'a farce'.
He told talkSPORT: "Looking at Spurs' squad, you cannot tell me that Dele Alli isn't better than Harry Winks, Lamela, even Sissoko.
"You know how Mourinho wants you - hard-working, up and down - and that's not really Dele Alli's game.
"I look at Dele Alli as a Frank Lampard-type midfielder. I'm not saying he's as good as Frank, but he gets in the box, gets on the end of crosses, does those late drives into the box - he gets goals.
"For whatever reason he can't seem to find that form. But to say he's got all these players and can't find a spot for Dele Alli is a farce.
"Dele Alli is better than some of those players he's got in the squad, but I think it comes down to trust. Right now, Mourinho trusts Winks and Sissoko a lot more than he trusts Dele Alli."
LATEST FOOTBALL NEWS
Goss
Arsenal news live: Chelsea raid rumours, Partey lifeline, Aouar in doubt, Laca to go?
listen
Simon Jordan tears into Man United's top brass, Maguire and Solskjaer in huge rant
GOSS
Tottenham transfer news live: Mourinho unsure over Bale debut, Orient clash in doubt
done deal
Arsenal sign Martinez replacement who could make his debut this week
goss
Chelsea news: Mendy having medical, Lampard on Kepa future, why Blues need Rice
NEWS
Palace deny Brewster bid, Alli not for sale, Woodward won't pay for United target
high scoring
Premier League record could be smashed this evening if goal-fest continues
big boots
Record breaking, trophy hero signed from Ligue 1 - history repeating for Chelsea?
REDS GREAT
Barnes says Mane could be bigger Liverpool legend than him… on one condition
GOSS
Liverpool transfer news live: Brewster bid reports denied, Wijnaldum Barca development
Alli's fall from favour has led to reports linking the 24-year-old with a shock move to Paris Saint-Germain.
Bent believes the England international should jump at the chance to make the switch to the French giants if it presents itself, insisting he will become a better footballer playing alongside Kylian Mbappe, Neymar and Marco Verratti at PSG.
He added: "It would be superb for him. We know the French league is not as competitive as the Premier League.
"But when you go and play with players like Mbappe, Neymar, Verratti, it's automatically going to lift his levels and make him a better player.
"A change of scenery could do him the world of good and going to that club, he'd be fantastic there."
Jose Mourinho's decision to overlook Dele Alli has been questioned by Darren Bent, who has told the midfielder a move to Paris Saint-Germain could be just what he needs.