These comments came back to haunt the Portuguese coach, whose side produced arguably their most disappointing display of the season up at St James' Park - their lead at the top of the Premier League table subsequently slashed to three points later in the day by reigning champions Manchester City.
Matic's replacement John Obi Mikel produced a typical John Obi Mikel performance - the Nigeria international simply isn't in the same class as his teammate - while Cesc Fabregas also disappointed without his classy central midfield partner alongside him.
Matic: Best signing of 2014
Matic, who re-signed for Chelsea in January after completing a £21 million move from Benfica, must go down as one of the best Premier League signings of 2014 - if not the very best.
It's no coincidence that previously unbeaten Chelsea lost their first match of the season without the Serbia international who had played every minute of Chelsea's Premier League campaign prior to the weekend.
Matic would have played the full 90 minutes against the Magpies, too, but was ruled out for picking up his fifth yellow card of the season in last week's 3-0 win over Tottenham.
Mourinho: 'We forget about Matic'
“We trust other people and we forget about Matic," Mourinho confidently told reporters last week. "He has a little bit of a holiday, a free weekend which he deserves very much, so he will return stronger.”
Without Matic in the side, though, Chelsea lack presence in midfield. A player whose hard work can sometimes go unnoticed with the likes of Eden Hazard, Diego Costa and the aforementioned Fabregas in the same side, the 26-year-old is just as important as any of them.
He shields Chelsea's back-four better than any other player in the league - that the Blues boast the second-best defensive record in England's top flight isn't solely down to Thibaut Courtois and his defenders - and retains possession superbly.
Chelsea would not have lost with Matic
This is a player you'll rarely - if ever - see knocked off the ball, while that cultured left foot of his is capable of picking out some wonderful passes.
Had Matic been on the pitch, Saturday's match in the north-east would have been an altogether different story.
And if he can steer clear of any more suspensions - plus injuries - then Chelsea should win the Premier League title at a canter.