The champions face Juventus at the San Siro on Friday with ground to make up in the league for the first time since October after last weekend's 2-2 draw at Fiorentina enabled AS Roma to go a point ahead of them in the standings.
Mourinho's reluctance to rotate a squad engaged on three fronts is widely seen as a big factor in the champions' slide in Serie A. They have picked up 14 points fewer than Roma so far in the second half of the season.
"It's not possible that they always play with the same team," Catania forward Giuseppe Mascara, who scored in the Sicilians' surprise 3-1 win over Inter last month, told Rai television.
"In the Champions League it's always the same, in the league it's always the same."
Mourinho gave some of his overworked troops, such as playmaker Wesley Sneijder and forward Diego Milito, a rest in Tuesday's Italian Cup semi-final second leg at Fiorentina.
Inter completed a 2-0 aggregate win but they will need high-flying Roma to cool off from their remarkable 23-match unbeaten run.
Mourinho, who will be without suspended Cristian Chivu against Juve, has also been accused of creating too much tension around his team.
TOUCHLINE BANS
The Portuguese has stopped speaking to the media after domestic games after a series of touchline bans for controversial gestures and outbursts and has suggested the Italian football establishment do not want Inter to win the title.
"Mourinho has got Inter used to a climate of tension ignited on demand," wrote La Gazzetta dello Sport correspondent Luigi Garlando. "By doing so he has created an addiction.
"While in the Champions League he has always managed to give the right charge, in Serie A he hasn't. It's either been too much and exhausting or too little and led to snoozy draws."
Another theory is that Mourinho has let complacency set in after his men led by nine points in February.
"One of the causes (of the domestic slide) was the conviction that the scudetto was already in the bag," former Italy coach Arrigo Sacchi wrote in his column in Gazzetta.
"Now there's (the Champions League semi with) Barcelona, which will require an extreme physical, psychological and competitive effort - 20 to 30 days of stress and tension that sooner or later they'll pay for."
Leaders Roma face a stiff test against city rivals Lazio on Sunday.
AC Milan, who are four points behind Roma in third, also have a tough game at Sampdoria earlier that day.
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