Tottenham took the lead after 25 minutes through Lucas Moura, who tapped home following an exquisite pass from Harry Kane, who claimed his fifth assist in two games.
The north London club had several chances to put the game to bed, particularly through Kane and Heung-min Son, who hit the woodwork twice.
With three games to follow this week, including mouth-watering ties against both Chelsea and Manchester United, an injured Son was withdrawn at half-time, with Tottenham losing their attacking impetus thereafter.
For all their dominance, they were made to pay as Newcastle were controversially awarded a penalty in the 93rd minute after substitute Andy Carrol's header hit the hand of Eric Dier from all of a yard away, with the England defender totally unaware and facing the other way.
Callum Wilson stood up and blasted the penalty beyond Hugo Lloris, with Mourinho subsequently marching straight down the tunnel.
🎙 - "Whoever is in involved in this - stop it. You're ruining football." @Carra23 is 𝙣𝙤𝙩 happy with the decision to give this as a penalty - your thoughts? 🤔
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The result leaves Tottenham in seventh place, missing an opportunity to momentarily claim second place.
However, with Chelsea to travel to the Tottenham Hotspur stadium within 72 hours, there will be no time to rest on what was a thoroughly disappointing result for Spurs and Mourinho.