Spurs missed the chance to return to the top three as Ivan Cavaleiro's header made it 10 points dropped from winning positions this season.
Mourinho teased Dele's involvement ahead of the game, praising his " professionalism and attitude" before adding: "I will not be surprised if next Wednesday Dele is playing with us."
But it was not to be as Mourinho turned to Erik Lamela and Carlos Vinicius as Spurs chased an equaliser, which never came.
After the game, Dele posted on Instagram a selfie of himself looking fed up.
While Dele's thoughts were more cryptic, Roberts - who made over 200 appearances for Spurs during the 1980s and won both the FA Cup and Uefa Cup - made his clear after the final whistle.
Sorry not to use dele crazy tonight when needed a goal.
— Graham Roberts (@GrahamRoberts4) January 13, 2021
He tweeted: "Sorry not to use dele crazy tonight when needed a goal. (sic)"
start dele next time im actually getting mad now 🤨 https://t.co/ZttbrlHdL5
— aj (@ajtracey) January 13, 2021
Rapper AJ Tracey was of similiar frustrating, tweeting with a raised eybrow emoji: "start dele next time im actually getting mad now (sic)"
Spurs are next in action on Sunday as they travel to bottom-of-the-table Sheffield United.
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