It was the imperious Ronaldo who inevitably made the breakthrough at Pride Park to send Manchester United back to the summit of the Barclays Premier League as they ran out 1-0 winners.
Earnshaw, making a rare start for the Rams this season, said: "The game was a real battle between Roy (Carroll) and Ronaldo, and Roy was winning it until the goal.
"You have to make it as hard as possible, but we're talking about one of the top three players in the world.
"You look at these last two seasons, and he has almost been toying with the Premier League. That's how good he has been. He has been toying with everyone."
It was more of the same on Saturday from the 23-year-old.
"Against us he missed a few chances. But he still managed to get the goal, and that's him," said Earnshaw.
"United create so many chances, and that's why he and they score so many goals.
"If they miss one, two, three chances, they know a fourth and a fifth will come - and so on. That's the difference."