The Premiership holders needed no help from top scorer Ronaldo and striker Wayne Rooney to outclass a lackluster Fulham.
Ferguson, who has an eye on midweek's Champions League tie with Lyon, was glad that his rotation planned worked well.
"The pleasing thing for me was that I was able to use my squad. We've got a massive game on Tuesday against Lyon and resting Rooney and Ronaldo was vital for us to do," the Scot told Sky Sports.
"But the team I picked showed a great desire for the game, they worked really hard.
"I don't think Fulham were a great threat to us in terms of inside the penalty box, but outside the box they played some good football and pressed the ball really well and gave us a test.
"Obviously scoring a goal right on half-time time killed them really. It was a good goal from Park Ji-Sung, his first of the year, so we're pleased with that."