Chelsea's 'Special One' started the mindgames in his first news conference after returning to Stamford Bridge by openly admiring the qualities of England striker Wayne Rooney in a move sure to have riled new United boss Moyes.
Mourinho and Chelsea turned the screw further by making bids for the unsettled forward although United and Moyes have continued to suggest he is not for sale.
However, the will-he-won't-he nature of the Rooney situation has hardly projected a united front at Old Trafford.
And Thursday's extraordinary comments by United boss Moyes, that his side's early fixtures might have been deliberately made more challenging, were the clearest sign yet that he is already feeling the pressure after taking over from Alex Ferguson in the close season.
"I hope it's not because Manchester United won the league quite comfortably last year that the fixtures have been made much more difficult," Moyes told the BBC.
"I find it hard to believe that's the way the balls came out of the bag, that's for sure."
Those barbed comments about the fixture list, in which United meet Chelsea, Liverpool and Manchester City in three of their opening five matches, appear a symptom of the pressure piling on Moyes as he seeks to retain the title secured by the now-retired Ferguson last season.
An inability to make any meaningful signings in the close season may have frustrated the Scot and is unlikely to have helped his mindset especially since neighbours Manchester City have been splashing the cash freely at the Etihad Stadium.
The Rooney saga, too, must surely be weighing heavily on Moyes.
LEGAL PROCEEDINGS
The Scot was forced to watch the player he used to manage at Everton, and with whom he had a very public falling out which led all the way to legal proceedings, start for England despite having been deemed unfit to play in any of United's pre-season matches.
Rooney missed Sunday's 2-0 Community Shield win over Wigan Athletic but England boss Roy Hodgson pronounced him fit to play in Wednesday's 3-2 friendly victory over Scotland and he featured for more than an hour at Wembley.
Such a scenario would have been unthinkable in Ferguson's reign. In fact the opposite was the general rule with the former United manager routinely exerting pressure to have players withdrawn from international squads because of knocks and niggles.
Certainly if Moyes had a sore tooth to be wobbled, Rooney was it. And Mourinho, whose mindgames with rival managers were a feature of his first spell at Chelsea, seized on it with both hands and twisted.
In his first news conference after returning to the west Londoners in June, Mourinho spoke of his admiration for the England striker.
The Portuguese has gone quiet on the 27-year-old in recent days, only confirming that Rooney was still a target and saying Chelsea would not relent in their pursuit.
"There is no time limit," Mourinho said last week. "We have our squad of strikers.
"We have identified the player as one we would like to have with us. We have done it in an ethical way and we are going to do that until the last day."
Moyes said last month that he welcomed the mindgames and that his upbringing had prepared him for it.
"If you're from Glasgow you quite enjoy those sort of things. So bring it on," he told reporters in Sydney last month.
But in English soccer's parallel mindgames league, Moyes's outburst on Thursday appeared as close to signalling a bloodied nose if not a first-round knockout.
(Editing by Tony Jimenez)
