"Shevchenko and Ballack have to give more because their status is not superior to that of the others," Mourinho told The Sun.
"Each is a champion," he added. "They have quality, status and fame. They're rich and have already won a lot of trophies. All that is an undeniable fact.
"But it's one thing their being the centre surrounded by 20 nobodies, and it's something else these two players arriving at a club where the others are already champions, famous and rich."